1903.] NATURAL SCIENCES OF PHILADELPHIA. 201 



varies, tlie average being smaller than Arkansas shells. The smallest 

 specimens measure 15 mm. diam., whorls -ih; the largest 18 mm. with 

 4f whorls. At Chadwick, Mo., the smallest specimens I have seen 

 were taken, varying from 14^ to 17^ mm. diam. 



^olygyra binneyana Pil?- 



Pilsbry, NautUus, XIII, p. 38 (August, 1899); Proc. A. X. S. Phila., 1900 

 p. 451; Ferriss, Nautilus, XIV, p. 28 (July, 1900). 



Poteau* Choctaw Nation, I. T.; Rich Moimtain.=^= Polk county, 



Ark. 



Polygyra appressa perigrapta Pils- 



Chester, Crawford county, and Petit Jean, Yell county. Ark. vSpeci- 

 inens typical but ratlier small, diam. 18-19Vmm. A specimen was 

 also sent from Gulf port, Miss. 

 Polygyra thyroides (Say). 



Cf. Proc. A. N. S. Phila.. 1900, p. 452. 



Seligman, Barry county. Mo. Small specimens of the globose 

 bucculenta form; diam. 15^ to 18 mm; umbilicus generally nearly 

 covered, as in P. clausa, but sometimes entirely closed. The speci- 

 mens have a decided resemblance to P. clausa. Two out of eight 

 adults have a small parietal tooth. 



Antlers, Choctaw Nation, I. T.; Poteau, in the same district, near 

 the Arkansas iDoundary. Small specimens, diam. 18 mm. Carrion 

 Crow Mountain, Pope county, also small. 



At Hardy, Sharp county, in northeastern Arkansas, two specimens 

 of a small form of thyroides were taken, measuring 17^V and 18 mm. 

 diam., and closely resembling P. clausa, from which they differ, how- 

 ever, in the more "dished" lip, less elevated contour, and slight angu- 

 lation of the front of the last whorl. One of these specimens is almost 

 imperforate. 

 Polygyra clausa (Say). 



Springfield, Green county. Mo. The specimens are quite typical. 

 This is. so far as I know, the southwestern extreme of the known 

 distribution of the species. Two specimens were taken at Hardy, 

 in northeastern Arkansas. In Missouri and Arkansas P. clausa is 

 sometimes very difficult to distinguish from the small form of P. 

 thyroides, which occurs in that region. This is the more remarkable 

 because the two species in other parts of the country are quite readily 

 distinguishable by the shells. 

 Polygyra pilsbryi Ferriss. PI. IX, figs. 1, 2, 3. 



Ferriss, Nautilus, XIV, p. 29 (July, 1900). 



Rich Mountain Station, Polk county. Ark., is thus far the onlv local- 



