242 



ON THE TOPOGRAPHY AND GEOLOOY 



TROOIIITA. Schum. ' . 



T. Sp. indet. ,^ . 



A single young specimen, smooth and ratlier high. 



CRYPT A. Humph. - ■ 



C. fo mi cat a. Linn., sp. 



Petollu, id. Linn. Syst., p. 1357 • ' ■ 



Grypta, id. IL and Ad. Gen. Eec. Moll. - ■ 



Rare. 



CAPULUS. Moutf. 



C. i n o r n a t u s. Gabb, n. s. 



Shell thin, expanded, nuclear AA'hoil distinctly incurved ; mcuth irregularly sub-circular, surface marked by 

 lines of growth and by obsolete radiating lines. Length .G inch, height .4 inch. 



A thin simple shell, with little of tangible characters except its small incurved 

 apex and barely visible radiating lines. - 



NERITINA. Lnm. 



N. viridis. Linn., Syst., p. 1254. 



A dozen specimens, all showing more or less of their color. 



■ EUTROPIA. Humph. ' ' " 



E. a 1 1 i s p i r a. Gabb, n . s. 



Shell small, spire elevated, about as long as the aperture, whorls six, very convex ; surfac3 polished, ai^erture 

 rounded, inner lip slightly encrusted. Length .15 inch. 



A beautifully formed little shell, which can be recognized by its very round 

 whorls and nearly circular aperture. My unique specimen shoAvs no trace of color. 



TURBO. Linn. 



T. D o m i n i c e n s i s. Gabb, n. s. 



Shell sub-globular, spire elevated, base imperforate, whorls about six or seven, round ; suture bordered by a 

 beaded rib. Entire surface marked by rounded revolving ribs, of which two on the side and one adjoining the 

 suture are generally larger than the others. All of these ribs, but more especially the large ones, are more or less 

 broken up into rows of beads. Mouth round, callous of the inner lip, thick and rounded ; outer lip simple. Height 

 and width about 1 inch. 



!N^earest in general character of the surface to Senectus Sj^engleriamis, but dis- 

 tinguished from it by the closely-placed beaded ribs and the presence of a strong 

 beaded rib adjoining the suture instead of a groove. The inner lip is different, and 

 the aperture is rounder and not expanded in front. ■ 



ASTRALIUM. Link. ' \ . - 



A. longispinum. Lam., sp. 



TrocJiu.s longispinus. Lam., A. S. V., Vol. IX., p. 123. 



Asiralium, id. Adams. _ . 



A single mould, fortunately in determinable condition. 



CYCLOSTREMA. Marryatt. ' 



C. striata. Gabb, n. s. 



Shell small, discoidal, spire depressed, umbilicus broad, perspective ; whorls about five, round, slightly flattened 

 near the suture. Aperture nearly circular ; surface marked by luimerous fine revolving lines. 



]N"earest to (f. (■'huivlifpra. Ad., l)ut more discoidal and with finer surface strife. 



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