44 



a little concave on both sides ; apex' moderately depressed, more so 

 on the riglit side ; whorls five, rather convex on the right side, sub- 

 angular on the left, with a well impressed suture; last whorl not 

 large, with the subangular periphery nearer to the right side ; aper- 

 ture semioval ; much advanced at the right extremity. This spe- 

 cies resembles P. pallidus Ad., which has a less number of whorls, 

 of which the last is much wider; that shell is also higher. 



Greatest breadth .365 inch ; least breadth .32 inch ; height of 

 the last whorl .09. 



Planorbis affinis. Shell discoidal ; horn color ; with coarse 

 striae of growth ; spire wide and moderately concave on both sides ; 

 apex very deeply depressed into a minute pit and invisible on the 

 right side, conspicuous on the left side ; whorls about five and one- 

 third, convex with a deep suture on the right side, on the left side 

 angular, with the suture at first on the angle for nearly three whprls 

 and then descending into an acute angular channel ; last whorl 

 rather large, moderately turned to the left ; aperture semioval ; 

 labrum moderately advanced on the right side. This shell is very 

 similar to P. lentus Say, of which it may possibly be a variety. Its 

 altitude is less, and the right side is more uniformly concave. Per- 

 haps this is a case of specific identity with plural origin. 



Greatest breadth .68 inch ; least breadth .535 inch ; height of 

 last whorl .21 inch. 



Var. a ; brownish red, with coarser striae of growth, the outer 

 whorl more sharply angulated, and higher. 



Greatest breadth .57 inch ; least breadth .455 inch ; height of 

 last whorl .22 inch. 



Cyclas Veatleyi. Shell oval ; horn color with a tinge of 

 brown ; extremely thin, with fine striae of growth ; valves very in- 

 equilateral, with a moderately convex disk ; anteriorly both short 

 and low, with a well rounded margin ; posteriorly very high and 

 subtruncated ; beaks small but prominent ; cardinal teeth small ; 

 lateral teeth moderately developed, somewhat remote. Very rare. 



Length .21 inch; height up the middle of the posterior side .15 

 inch; breadth .105 inch, 



Cyclas pygm.ea. Shell oval; color* ?; not very thin pro- 

 portionately to its size, with microscopic striae of growth; valves 

 somewhat inequilateral, with a very convex disk; anteriorly short 



' I was unable to find any living or fresh specimens. 



