154 GNATHODON. 



or oval, transverse, slightly ventricose, equi valve, inequilateral ; 

 margins close, rounded anteriorly, somewhat acuminated poste- 

 riorly ; hinge teeth, three in each valve, of which the central 

 in one, and the posterior in the other, are bifid ; muscular im- 

 pressions anterior, elongated, marginal ; posterior sub -quadrate ; 

 palleal impression, having a long sinus ; ligament oblong, ex- 

 ternal ; epidermis thin, horny, green, folded over the margins. 

 — Obs. This shell, of which only one species is known, inhabits 

 some of the rivers in China. C. Chinensis, fig. 64. 



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



GLOBOSE. (Globosus.) Rounded like a globe or ball, as the 

 species of Helix, represented in fig. 268. 



GLOBULARIA. Sw. A sub-genus of Natica, consisting of 

 globose species. (Sw. p. 345.) Ex. N. Lineata, fig. 328. 



GLOBULUS. Sow. Min. Con. Ampullaria, Auct. 



GLYCIMERIS. Lam. Farn. Solenacea, Lam. Pyloridea, Bl. — 

 Descr. Equivalve, transverse, oblong, thick, compressed, gaping 

 at both extremities ; hinge callous, without teeth ; ligament 

 large, external, prominent; epidermis thick, black, horny, folded 

 over the margins ; muscular impressions two, distant, running 

 into the irregular palleal impression which unites them. — Obs. 

 But few species of this singular genus are known ; Lamarck 

 describes two species from the Northern Seas. Blainville is of 

 opinion that they belong to the family of the Nayades. Fig. 

 67, G. Siliqua. 



GNATHODON. Gray. (YvclQoq, gnathos, jaw-bone ; oSog, oSovtoq 

 odontos, tooth.) Fam. Mactracea, Lam. — Descr- Ovate, poste 

 riorly angulated, equivalve, thick, ventricose, inequilateral 

 covered with a greenish brown epidermis ; umbo distant, pro 

 minent ; hinge having in one valve a sharp, angular, notched, 

 cardinal tooth, and two lateral teeth, the posterior of which is 

 elongated, and the anterior angulated, tortuous, shaped like 

 a jaw-bone ; in the other valve, two cardinal and two lateral 

 teeth, the anterior of which is wedge-shaped ; ligament internal, 

 cuneiform, placed in a deep cardinal pit, proceeding from 



