168 HEMITEOCHUS. 



HEMICYCLOSTOMATA. Bl. The fourth family of Asiplio- 

 nibranchiata, El. described as " more or less globular, thick, 

 flattened on the tinder side ; spire very short ; aperture large, 

 semilunar, entire ; its outer edge hollowed ; its inner or columel- 

 lar edge straight, sharp and septiform." This family answers to 

 the genus Nerita of Linngeus, and to the family Neritacea of 

 Lamarck. It contains the genera Natica, Nerita, Neritina, and 

 Navicella, 



IIEMIMACTEA. Swainson, 1840. 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 |, distinct, lateral, striated : connected to 

 the Glychneri. H. gigantea, Lam. v. 472. No. 1. grandis, Sw. 

 Sp. Nov." Sw. p. 369. 



HEMIMITEA. Sw. A sub-genus of Paludomus,Sw. (Melanianae.) 



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

 " Tubercles or undulations on the hinge margin. H. undulatus, 

 purpurascens and areolata." 



HEMIPECTEN. Adams and Eeeve. MoUusca of the Samarang. 

 A genus belonging to the family of Pectinidse, thus described, 

 "attached, ineequivalve, irregular, hyaline, upper valve simple 

 anteriorly, very slightly auriculated posteriorly; lower valve 

 simple anteriorly, conspicuously auriculated posteriorly, deeply 

 sinuated and denticulated beneath the auricle ; hinge edentulate, 

 ligament slightly marginal with a small cartilage in a central 

 cavity. Hemipecten Eorbesianis, Reeve. Conch. Icon." Our 

 Plate xxvii. fig. 580. 



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

 " General shape of Melania ; but the base of the aperture is 

 contracted and emargiaate ; outer lip crenated. H. lineolatay 

 Griif. Cuv. xii. pi. 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." 



HEMITEOCHUS. Sw. A sub-genus of Geotrochus, Sw. H. 

 hsemastroraa. Sw. p. 331. 



