252 MELANIID^. 



diately separable from the peculiarly North American group 

 Strepomatidse, which they much resemble in the characters of 

 the shell. Mainly of Indo-Pacific, African and Polynesian dis- 

 tribution, they number several hundred existing species, besides 

 a number of fossil forms commencing with the Jurassic period. 



Paludomus, Swainson. 



Etyni. — Palus, a marsh, and domus, home. 



Syn. — Rivulina, Lea. 



Distr. — 25 sp. Ceylon, India. P. conicus. Gray (Ixx, 74). 



Shell Paludiniform ; columella callous, scarcely planulate. 

 Operculum concentric, with spiral, sinistral, subcentral nucleus. 



PHiLOPOTAMis, Layard. (Heteropoma, Benson.) Shell fre- 

 quenth^ globose, but spire exserted ; columella callous, scarcely 

 planulate. Operculum subspiral ; nucleus basal, dextral, sub- 

 marginal. Distr. — 9 sp. Ceylon, Sumatra. P. nigricans^ Reeve 

 (Ixx, 75). 



TANALiA, Gray. (Ganga, Layard. Serenia, Benson.) Shell 

 globose, neritiform ; columella wide, planulate. Operculum 

 lamellated, nucleus dextral, median, marginal. Distr. — 7 sp. 

 Ceylon. P. loricata^ 'Reeve (Ixx, 76). 



STOMATODON, Beusou. Shell globose, columella wide, base 

 truncate and furnished with a prominent tooth. Operculum (?). 

 Distr. — P. Bensoni, Brot. (Ixx, 77). Southern India. 



Melania, Lam. 



Etyrti — Melania^ blackness (from melas). 



Distr. — 400 sp. So. Europe, India, Philippines, Pacific Islands. 



Shell turreted, apex acute ( unless eroded) ; whorls ornamented 

 with strise or spines ; aperture oval, pointed above ; outer lip 

 sharp, sinuous. Operculum subspiral. 



MELANELLA, Swainsou. Shell ovoid, with elevated spire ; 

 aperture large, its base subproduced and rounded. Operculum 

 paucispiral, nucleus subspiral. M. glans, von dem Busch (Ixx, 

 78). Java. Includes 31. Hollandri^ Per., and M. parvula, 

 Schmidt ; European species. 



ACROSTOMA, Brot. Shell fusiform, subbiconic ; aperture 

 angulately produced at the base. Operculum (?). M. Hugelii, 

 Phil. Java, India. 



PACHYCHiLUS, Lea. Shell turi-eted or subfusiform ; aperture 

 ovate, its base subproduced, peristome usually thickened. Oper- 

 culum three- to four-whorled, with subcentral nucleus, Mexican, 

 Central American. M. laevissima^ Sowb. (Ixx, 79). 



AYLACOSTOMA, Spix. ( Aulacostoma, Agassiz.) Whorls cari- 

 nated or shouldered near the suture. South America. M. 

 scalaris, Spix (Ixx, 80). 



SULCOSPIRA, Troschel. Shell ovately turreted, sulcate-striate ; 



