142 v THE CHICAGO ACADEMY OF SCIENCES. 



For jaw and radula see the various species described.f 



Distribution: North America (exclusive of some parts of 

 the southwestern U. S.), Cuba, Bahamas and Bermuda." (Pils- 

 bry.) 



FIG. 15. 



Genitalia of POLYGYRA. (P. ANDREWS:, after Binney, Bull. Mus. 

 Comp. Zool., Vol. XI, No. 8, pi. iii, Fig. E.) ag, albuminiparous gland; e, 

 duct from testicle; gb, genital bladder; o, ovary; ov, oviduct; or, orifice; pr, 

 prostate gland; ps, penis; r, retractor muscle; t, testicle; vd, vas deferens. 



KEY TO SPECIES OF POLYGYRA. 



A. Aperture without heavily developed teeth. 



a. Shell encircled by color lines. 



1. Perforate profunda 



2. Imperforate , multilineata 



b. Shell plain horn-colored. 

 *Shell large. 



1. Perforate, a small denticle on the parietal wall thyroides 



2. Imperforate, globose, parietal wall toothed, aperture 



widely lunate exoleta 



3. Imperforate, depressed globose, tooth generally lack- 



ing, aperture narrowly lunate albolabris 



**Shell small, less than half size of (*). 



1. Perforate , clausa 



2. Imperforate pennsylvanica 



fFor a general consideration of the jaws and radulse of pulmonate mullusks, see an ex- 

 cellent paper by W. G. Binney in Proc. Phil. Acad., 1875, pp. 140-243. 



