142 THE NAUTILUS. 



Somatogyi-us pilshryaniis n. sp. PI. v, figs. 20 and 21. 



Shell small, gibbous-globose, scarcely perforate, rather thin, light 

 yellow-horn colored, smooth, lines of growth very fine. Spire short, 

 conic, obtuse. Whorls d^, those of the spire convex, separated by a 

 well-impressed suture, body whorl large, very convex, gibbous. 

 Aperture large, widely ovate, obtusely angled above and regularly 

 rounded below. Umbilical region impressed. Umbilicus a mere 

 chink. Columella concave, with a heavy, flat callus, which becomes 

 thin and transparent on the parietal wall. Alt. 3, diam. 3 mm. 



Tallapoosa river, Tallassee, Ala. 



This is another of the new species discovered by Mr. Hinkley. I.t 

 occurred quite abundantly and is a well marked and distinct form. 

 It is related to S. parvulus, Tryon (PI. v, figs. 22 and 23), in gen- 

 eral appearance, but differs in the wide, gibbous body whorl, more 

 obtuse apex and in the heavy, flat, columellar callus, >S'. parvuhis 

 being more acutely conical, with the body whorl regularly rounded 

 and with a narrow, rounded, columellar callus. Dr. Pilsbry has 

 kindly compared it with the types of Tryon's species and concurs in 

 its specific distinctness. I take great pleasure in naming it after him. 



A 5EW SUBSPECIES OF POLYGYRA TRIDENTATA. 

 BY n. A. PILSBRY. 



Polygyra tridentata discoidea n. subsp. 



The shell is larger than tridentata, more depressed, the spire 

 usually nearly flat. Whorls 5^, closely and sharjdy striate. Umbili- 

 cus more widely expanding at its opening, showing more of the pre- 

 ceding whorl. The aperture is more or less " dished," the parietal 

 tooth directed towards the upper lip-tooth, wliich while varying 

 somewhat in shape has a tendency to be i-ather Avide and flat-topped. 

 The lower lip-tooth is more acute, both being strictly marginal. 



Alt. 9^, diam. 20^ mm. 



Alt. 8, diam. 19 mm. 



Alt. 8^, diam. 18^ mm. 



Charleston Landing, Clarke Co., Soutliern Indiana. Cotypes in 

 coll. A. N. S. P. and of L. E. Daniels. 



During a recent visit, Mr. G. H. Clapp called my attention to the 

 form of P. tridentata found around Cincinnati, and widely known in 



