18 Descriptions of Thirty Supposed New Species and 



of growth well marked. Spire with outline moderately con- 

 vex. Whorls 5, quite convex, with a deep suture ; last 

 whorl well rounded, and aperture almost circular, except 

 for the interruption of the penult whorl. Aperture out of 

 the plane of the axis, and outer lip very little projecting 

 from the penult whorl. Umbilicus very small. 



This species (?) is like unto^T. fynrbiniformis, Pfr., but 

 its divergence is less, its size, less, and its aperture and ex- 

 pansion of lip, much less ; and angularity on last whorl is 

 almost entirely wanting. It may be only an extraordinary 

 var. of H. turbiniformis, and if so, I claim its name, as 

 a var. only. At present I have only four specimens, inclu- 

 sive of one sent to the British Museum. 



Mean divergence 68 (largest specimen,) height .2, 

 greatest breadth .16, least breadth .15. 



Habitat, Newton, St. Andrew's mountains. 



Named in honor of Dr. GILBERT Me. NAB, of Kingston, 

 Jamaica. 



PLANORBIS AFFINIS, A very long way up the Black- 

 River, in St. Elizabeth, about Channer's wharf, near Elim 

 Estate, occur very large specimens of this shell. Greatest 

 breadth .8. 



PLANORBIS ANGULATUS. Shell like PI. 

 (ADAMS, Cont. Conch p. 43,) but much larger, like PL 

 vortex, Mull : (Brown's British Shells, p. 22.) but the an- 

 gle of the aperture or of the periphery is more acute, and 

 more directly over the centre of the whorl, and the lip is 

 less turned up towards the apex. 



Shell dis-coidal, and excessively flattened : deepish brown, 

 semi-transparent color : with microscopic crowded trans- 

 verse strise of growth. Spire slightly concave, almost planu- 

 late from the 1st to the 6th whorl. It then becomes slightly 

 convex. The outer whorl angular, with a very slight, 

 almost microscopic, canal running close to the periphery on 

 the upper side. Under side much more concave than the 

 upper side. Apex conspicuous on both sides. Whorls 7 ; 



