254 MELANIIDiE. 



somewhat doubtful ; it may belong to the Rissoidse. M. Hupen- 

 sis, Gredler (Ixx, 92). 



Ptychostylus, Sandberger. 

 Didr. — P. harpseformis^ Dunker. Wealden, Europe, 

 Shell egg-shaped, with scalariform, sharp spire; whorls ribbed 



transversely ; mouth small, acutely angular behind, somewhat 



wider and rounded in front ; columella folded. 



DoRYSSA, H. and A. Adams. 



Distr. — 1*1 sp. Eastern South America. D. brevior, Troschel 

 (Ixxv, 93). 



Shell turreted, longitudinally plicate, decussated by revolving 

 sulcations ; aperture eifused at the base, right margin uncinately 

 produced. Operculum spiral with sinistral subcentral nucleus (?). 



Claviger, Haldeman. 



Syn. — Vibex (Oken), Gray. 



Distr. — 1 sp. Africa. G. aurita, Lam. (Ixxi, 94). 



Shell turreted, with revolving caringe or tubercles; aperture 

 subproduced at the base, subcanaliculate, outer margin sinuous, 

 two to four plicae within. Operculum paucispiral ; nucleus basal, 

 submarginal, sinistral. 



TiPHOBiA, E. A. Smith. 



Distr. — Lake Tanganyika, Africa. F. Horei, Smith (Ixxi, 95). 



Shell subturbinate, spire depressed ; whorls flattened above, 

 angulated and spinose ; axis and aperture prolonged into a 

 channeled beak. 



Similar in form to the American genus lo. The operculum is 

 unknown. It has been referred temporarily to the family Mela- 

 niidse, but is quite as closely allied, I think, to the fresh-water 

 division of the Cerithiidse, and especiallj^ to the Siamese genus 

 Brotia. 



Hemisinus, Swainson. 



Syn. — Basistoma, Lea. Tania, Gray. 



Distr. — 36 sp. So. and Central America, W. Indies, Seychelles, 

 Australia. H. lineolatus. Wood (Ixxi, 96). 



Apei'ture canaliculated at the base, columella not callous. 

 Operculum paucispiral ; nucleus basal, sinistral, marginal or 

 submarginal. 



VERENA, H. and A. Adams. Shell turbinated, shouldered and 

 coronated, spirally striate; aperture subtruncated anteriorly, 

 forming a short, wide canal. South America. H. crenocarina, 

 Morie. (Ixxi, 9t). 



Melanopsis, Ferussac. 



Syn — Bulliopsis, Conrad. Coptost3dus and Campylostylus, 

 Sandb. 



