A Conchological Manual, George Brettingham Sowerby [little readers .TXT] 📗

HELICOPHANTA. Fer. A sub-genus of Helix, consisting of ear-shaped

   species with large open apertures.

 

   HELICOSTYLA. Fer. A sub-genus of Helix, consisting of species with

   numerous whorls, as H. Epistylium, fig. 281.

 

   HELISOMA. Sw. A sub-genus of Planorbis. Sw. p. 337.

 

   HELIX. Auct. _Fam._ Colimacea, Lam.--_Descr._ Orbicular, light,

   generally globular; spire short, last whorl ventricose, aperture

   oblique, peritreme reflected, interrupted by the most prominent part of

   the body whorl; columella confluent with the outer lip, and contiguous

   to the axis of the shell. No operculum; a thin epidermis.--_Obs._ The

   land shells composing this genus are found in all parts of the world;

   the common snail, H. Aspersa, is well known as a destructive animal in

   our gardens. The genera Helix, Achatina, Bulinus, Clausilia, Anostoma,

   &c., have been united under one generic name by De Ferussac, and again

   divided under the following sub-generic names, each of which we shall

   illustrate by a figure. GENUS HELIX: _Sub-genus_ 1, _Helicophanta_,

   consisting of species with large apertures, like Vitrina; Helix

   brevipes. _S. gen. 2_, _Cochlohydra_, Succinea Amphibia, Drap. _S. gen.

   3_, _Helicogena_, consisting of the common species with the last whorl

   large; Helix Hæmastoma, H. Contusa, (Streptaxis, Gray,) H. Aspersa. _S.

   gen. 4_, _Helicodonta_, consisting of species with teeth or folds on

   the columella; Polydonta, Montf. Anostoma, Helix Nux-denticulata. _S.

   gen. 5_, _Helicigona_, Carocolla, Geotrochus. _S. gen. 6_, _Helicella_,

   consisting of depressed species with a large umbilicus; H. Citrina

   (Naninia, Gray.) _S. gen. 7_, _Helicostyla_, consisting of species with

   a simple aperture, like the Helicogenæ, but with the whorls increasing

   very gradually; H. epistylium. _S. gen. 8_, _Cochlostyla_, Bulinus. _S.

   gen. 9_, _Cochlitoma_, Achatina. _S. gen. 10_, _Cochlicopa_, Polyphemus

   Glans. _S. gen. 11_, _Cochlicella_, Bulinus decollatus. _S. gen. 12_,

   _Cochlogena_, Azeca tridens. _S. gen. 13_, _Cochlodonta_, Pupa Uva. _S.

   gen. 14_, _Cochlodina_, Clausilia macascarensis, Balea fragilis. The

   last three sub-genera are included in the genus Odostomia of Fleming.

   We give an example of each of these sub-divisions, for the sake of

   presenting the reader with the principal variations to which the genus

   is subject. The established genera will be characterized in their

   places. Fig. 254 to 281.

 

   HELIXARION. Fer. VITRINA, Drap. Differing from Helicolimax in the

   structure of the animal. Fig. 262.

 

   HEMICARDIUM. Cuv. ([Greek: hêmisus], _hemisus_, half, [Greek: Kardia],

   _cardia_, heart.) CARDIUM Hemicardium, fig. 123**, and several similar

   species.

 

   HEMICYCLA. Sw. A sub-genus of Helix.

 

   HEMICYCLONOSTA--see CARDILIA.

 

   HEMICYCLOSTOMATA. Bl. The fourth family of Asiphonibranchiata, Bl.

   described as "more or less globular, thick, flattened on the under

   side; spire very short; aperture large, semilunar, entire; its outer

   edge hollowed; its inner or columellar edge straight, sharp and

   septiform." This family answers to the genus _Nerita_ of Linnæus, and

   to the family Neritacea of Lamarck. It contains the genera Natica,

   Nerita, Neritina, and Navicella.

 

   HEMIMACTRA. Sw. A sub-genus of Mactra, thus described: "General form of

   _Mactra_; but the cardinal teeth entirely wanting; cartilage internal,

   central, in a large triangular cavity; lateral teeth 2/1, distinct,

   lateral, striated: connected to the _Glycimeri_. H. gigantea, _Lam._ v.

No. 1. grandis, _Sw._ Sp. Nov." Sw. p. 369.

 

   HEMIMITRA. Sw. A sub-genus of Paludomus, Sw. (Melanianæ.)

 

   HEMIODON. Sw. A sub-genus of Anodon, described as having "Tubercles or

   undulations on the hinge margin. H. undulatus, purpurascens and

   areolata."

 

   HEMISINUS. Sw. A sub-genus of Melania, thus described: "General shape

   of _Melania_; but the base of the aperture is contracted and

   emarginate; outer lip crenated. H. lineolata, Griff. Cuv. xii. pl. 13.

   fig. 4."

 

   HEMITOMA. Sw. A sub-genus of Emarginula, thus described: "Patelliform;

   the fissure not cut through the shell, but merely forming an internal

   groove. H. tricostata, _Sw._ Sow. Gen. fig. 6."

 

   HEMITROCHUS. Sw. A sub-genus of Geotrochus, Sw. H. hæmastoma. Sw. p.

   331.

 

   HEPTALASMIS. Leach. ([Greek: Hêpta], _hepta_, seven; [Greek: elasma],

   _elasma_, plate) A small shell resembling Pentelasmis, from which it

   differs in the number of valves, being composed of seven valves

   according to Leach, and of eight according to Gray, who counts the

   dorsal valve, which is jointed, as _two_, and names his genus

   Octolasmis. Fig. 41, H. Warwickii.

 

   HERCOLES. Montf. A microscope shell, appearing from De Montfort's

   figure to resemble TROCHUS _Imperialis_ in shape.

 

   HERION. Montf. LENTICULINA, Bl. Microscopic.

 

   HERMAPHRODITA. Bl. The third sub-class of Paracephalophora, Bl. divided

   into, Sect. 1, _symmetrical_, containing the orders Cirrobranchiata and

   Cervicobranchiata; Sect. 2, _non-symmetrical_, order, Scutibranchiata.

 

   HERMES. Montf. A genus composed of CONUS _Nussatella_, Auct. and other

   elongated, cylindrical, striated species. Fig. 460.

 

   HETEROBRANCHIATA. Bl. The fourth order of the class Acephalophora, Bl.

   containing no testaceous mollusca.

 

   HETEROPODA. Lam. The fifth order of the class Mollusca, Lam. This order

   contains but one genus of shells, viz. Carinaria, fig. 488.

 

   HETEROSTEGINA. D'Orb. A genus of microscopic Foraminifera.

 

   HIATELLA. Daud. Fam. Lithophagidæ, Lam. A genus composed of species of

   Saxicava, Auct. which have sharp, angulated, posterior ridges, a

   circumstance which occurs to many species in a young state, which

   afterwards become rounded off. Fig. 95, Hiatella biaperta.

 

   HIATULA. Sw. A genus proposed to include those species of Oliva, Auct.

   which have widened apertures. _Ex._ O. Subulata, fig. 458.

 

   HIBOLITHES. Montf. A genus composed of species of Belemnites, Auct.

   which are swelled towards the apex, and contracted near the centre. B.

   Hastatus, Auct. fig. 468.

 

   HIMANTOPODA. Schum. MALLEUS, Auct.

 

   HINGE. The edge of the bivalve shells near the umbones, including the

   teeth and ligament.

 

   HINNITES. Defr. A generic name proposed for PECTEN PUSIO, Auct.

   remarkable for the irregularity of the outer surface, which would

   almost lead to the belief of its being an attached shell. Fig. 173, H.

   Pusio.

 

   HIPPAGUS. Lea. (_Horse boat._) A minute fossil shell, resembling

   Isocardia in form, but destitute of hinge teeth. H. Isocardioides, fig.

   128.

 

   HIPPOCHRENES. Montf. Species of ROSTELLARIA, Auct. with the outer lip

   spread. Fig. 403. R. Columbaria.

 

   HIPPONYX. ([Greek: Hippos], _hippos_, horse; [Greek: onux], _onyx_,

   nail or hoof.) _Fam._ Rudistes, Lam.--_Descr._ Inequivalve,

   sub-equilateral, rather irregular, destitute of ligament and hinge

   teeth; lower valve attached, flat, sub-orbicular, with a muscular

   impression, composed of two lunulate portions, meeting at one

   extremity, and presenting the form of a horse-shoe; upper valve

   conical, with the apex inclined backwards, and the muscular impression

   marginal.--_Obs._ The earlier naturalists having only met with the

   upper valve of these shells, placed them among the patelliform

   univalves; to some of which, particularly Pileopsis, they bear a very

   strong resemblance. The species of Hipponyx are numerous, and till

   lately only known in a fossil state. The recent species belong to

   tropical climates: the fossil species are found in the tertiary beds.

   Fig. 199, H. Cornucopia.

 

   HIPPOPODIUM. Conybeare. _Fam._ Cardiacea, Lam.--_Descr._ Equivalve,

   obliquely transverse, heavy, deep, inequilateral, umbones incurved;

   ventral margin sinuated, so as to give a bilobed appearance to the

   shell; hinge incrassated, with one rugged oblique tooth.--_Obs._ These

   fossils are found in the upper beds of Lias. Fig. 129, H. Ponderosum.

 

   HIPPOPUS. Lam. ([Greek: Hippos], hippus; [Greek: pous], _pous_, foot.)

   _Fam._ Tridacnacea, Lam.--_Descr._ Equivalve, inequilateral, regular,

   subquadrate; lunule closed, flat, with crenulated edges; ventral margin

   deeply undulated; external surface fluted, with radiating ribs, which

   are transversely fringed with rows of tubular spines; hinge margin

   thick, with two long, compressed posterior lateral teeth in one valve,

   three in the other; ligament marginal, external.--_Obs._ The shell thus

   described is rightly separated from Tridacna, on account of the

   anterior dorsal margins being closed; whereas in Tridacna there is a

   wide hiatus. Only one species of this genus is known, which receives

   its name from its resemblance in form to a horse's foot, when held with

   the flat anterior dorsal margin downwards. Few shells are found to

   concentrate so many beauties as the Hippopus Maculatus, commonly called

   the Bear's-paw-clam; the delicate whiteness of the interior, the

   undulating edge, the radiated fluted columns, adorned at intervals by

   crisped fringes, and the richness of the variegated colouring, are such

   as to secure the admiration of the most superficial observer. From the

   Indian Archipelago. Fig. 156, H. Maculatus.

 

   HIPPURITES. Montf. _Fam._ Orthocerata, Lam. Rudistes, Bl.--_Descr._

   Tabular, rude, irregular, attached; lower valve cylindrical, more or

   less lengthened, apparently divided into sections by septa (considered

   by some authors as merely projecting layers of growth) having one or

   two lateral tubes within; upper valve round, flat, fixed on the

   aperture of the tubular valve like an operculum.--_Obs._ This genus is

   known only in a fossil state, and but very imperfectly. Lamarck places

   it among his chambered Cephalopoda, &c. De Blainville, considering it a

   true Bivalve, enumerates it among his Rudistes. Cretaceous group. Fig.

   198, H. Cornucopia.

 

   HORTOLUS. Montf. SPIROLINA, Lam. Microscopic.

 

   HYALÆA. Auct. (_Hyalus_, glass.) _Fam._ Pteropoda, Lam. Thecosomata,

   Bl.--_Descr._ Globose, glassy, transparent, with a triangular opening

   at the upper part where the dorsal portion advances beyond the ventral;

   ventral portion vaulted; dorsal more flat; lower extremity

   tridentate.--_Obs._ The singular structures composing this genus were

   formerly taken for bivalves, and named Anomia Tricuspidata, &c. They

   are now known to belong to the class of molluscous animals, called

   Pteropoda, from the wing-shaped organs of locomotion. A species of

   Hyalæa occurs in Sicily in a fossil state. Recent species are found in

   the Mediterranean, Atlantic, and Indian Oceans. Fig. 226, H.

   Tridentata.

 

   HYALINA, Studer. VITRINA, Drap.

 

   HYALINE. (_Hyalus_, glass.) Glassy, thin, transparent--_Ex._ Carinaria

   Mediterranea, fig. 488.

 

   HYDROBRANCHIATA. Bl. The first section of the order Gasteropoda, Lam.

   containing Molluscs which breathe water only; divided into the families

   Tritoniana, Phyllidiana, Semi-phyllidiana, Calyptracea, Bullæana, and

   Aplysiana.

 

   HYGROMANES. Fer. A sub-division of Helix, containing H. limbata, Auct.

   &c. Gray's Turton, p. 143.

 

   HYRIA. Lam. A genus composed of species of Nayades, distinguished by

   their alated dorsal margins, and lamellated lateral teeth. South

   America. HYRIA corrugata, fig. 143, Hyria Syrmatophora, fig. 144.

 

   HYRIDELLA. Sw. A genus of "Hyrianæ," Sw. described as differing from

   HYRIA, Auct. in having a cardinal as well as a lateral tooth in each

   valve. Sw. p. 380.

 

   HISTRIX. Humph. RICINULA, Auct.

 

   JANERA. Schum. A genus composed of species of Pecten, Auct. having

   oblique plicæ or calli on each side of the ligamentary pit. _Ex._ P.

   plica, fig. 172. Decadopecten, Rüppell.

 

   JANTHINA. Auct. (_Janthum_, a violet.) _Fam._ Neritacea, Lam.

   Oxystomata, Bl.--_Descr._ Sub-globose, thin, fragile; spire short,

   consisting of few whorls; aperture angulated, at the anterior junction

   of the inner and outer lips; columella tortuous, contiguous to the

   axis; outer lip thin, sinuated in the centre.--_Obs._ The shells

   composing this genus are celebrated for their beautiful purple colour.

   The animal possesses a small vesicular process, which keeps it floating

   on the surface of the water; it exudes a purple secretion when

   irritated. It is occasionally floated on to the shores of most

   temperate and tropical countries. Fig. 333, J. Fragilis.

 

   JATARONUS. Adanson. CHAMA, Auct.

 

   IBERUS. Montf. CAROCOLLA, Lam.

 

   IBLA. Leach. _Fam._ Pedunculated Cirripedes, Lam.--_Descr._ Four

   valves, posterior pair elongated, anterior pair short, triangular;

   pedicle cylindrical, contracted at the base, hairy.--_Obs._ I.

   Cuveriana (fig. 40) is brought from Kangaroo Island.

 

   ICTHYOSARCOLITES. Desmarest. _Fam._ Ammonacea, Lam.--_Descr._

   Chambered, slightly arcuate, laterally compressed; septa simple,

   leaving triangular articulations imbricated like the thick muscles of a

   fish.

 

   JESITES. Montf. A minute fossil resembling GALEOLARIA.

 

   ILOTES. Montf. ORBICULINA, Bl. A genus of microscopic Foraminifera.

 

   IMBRICARIA. Schum. CONOHELIX, Sw.

 

   IMBRICATED. (_Imbrex_, a tile.) A shell is said to be imbricated when

   the superficial laminæ are arranged over each other in the manner of

   tiles.

 

   IMPERATOR. Montf. A genus composed of species of the genus TROCHUS,

   Auct. with whorls angulated and stellated, having an umbilicus. _Ex._

Imperialis. Some of the shells named Imperator in the British Museum

   belong to the genus Calcar, Montf. having no umbilicus.

 

   IMPRESSION. See MUSCULAR IMPRESSION.

 

   INCRASSATED. (_Crassus_, thick.) Thickened, as the hinge of Glycimeris,

   fig. 67.

 

   INCURVED. Turned inwards or bent forwards. Applied to symmetrical

   shells, when the point of the apex turns towards the anterior

   extremity, as in Patella. The apex of a shell is said to be incurved

   when it is bent inwards, but not sufficiently so to be described as

   spiral. _Ex._ Ammonoceras, Lam. fig. 477.

 

   INDENTED. (_In_, in; _dens_, a tooth.) Exactly the reverse of DENTATED;

   meaning a series of small cavities, such as might be produced by the

   entrance of teeth. The cast of a dentated surface would be indented.

 

   INEQUILATERAL. (_Æquus_,