154 GNATHODON. 



or oval, transverse, slightly ventricose, equivalve, 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. Fam. 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. (Tvadog, gnathos, jaw-bone ; odog, o^ovtoq 

 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 



