SIMl'ULOPSIS. 213 



colored. Type S. portoricensis. Greater Antilles and 

 Mexico. (See p. 223.) 



Section SIMPULOPSIS. 



Species of South America and Trinidad. 



Key to species. 



a. Shell smooth or nearly so, about as wide as high ; whorls 3^. 



atrovirens, p. 213. 

 a 1 . Shell longitudinally corrugated or folded, not decussate. 



b. Higher than wide, the spire prominent, whorls about 4^ ; 

 folds coarse, irregular and low. sulculosa, p. 214. 



b 1 . Diameter about equal to or exceeding the width ; whoils 

 3 to 4. 



c. Folds close, subregular and strong ; whorls 3 to 3^. 

 d. Diam and longest axis of aperture exceeding 

 alt.; spire very short, low ; outer lip inserted 

 above periphery of penult, whorl. 



braziliensis, p. 215. 



d l . Diam. exceeding alt.; spire short; outer lip in- 

 serted at periphery of penult, whorl. 



obtusu, p. 216. 



d*. Diam. and alt. about equal ; spire conic ; 

 length of aperture less than that of shell. 

 e. Olive or olive-brown ; alt. about 14 mill. 



rufovirens, p. 216. 

 e 1 . Light green ; alt. 9 to 10 mill. 



cornigata, p. 217. 



c 1 . Folds strong, irregular ; whorls 4 : alt. 17^, diam. 24 

 mill. miersi, p. 218. 



a 2 . Shell corrugated and decussate. 



b. Irregularly plicate, with extremely fine spiral strite ; 



whorls 4^; alt. and diam. about^equal ; alt. 20, diam. 19 



mill. iryoni, p. 218. 



b 1 . Closely plicate, with spiral sulci ; whorls 4^; alt. 11; 



diam. 12^ mill. decussata, p. 218. 



S. ATROVIUENS (Moricand). PI. 64, figs. 79, 80. 



Shell semi-oval, ventricose, excessively thin, being mainly cuticu- 

 lar ; olive-green or reddish-brown, becoming paler on the spire ; sur- 



