THE NATURAL HISTORY SURVEY. 159 



Animal: Blackish above and on head and eye-peduncles, 

 yellowish-white on base and foot; foot long and narrow, 32 

 mill, long and 4 mill, wide (11910); eye-peduncles long and 

 slender, tapering; heart situated on direct line drawn from the 

 umbilicus' to the upper termination of the peristome, beats 

 eighty-eight per minute regular. 



Jaw. Similar to that of thyroides, with ten ribs. 



Radula formula: 3 r 2 + li i_|_i_ + V+ (43-1-43); similar 

 to that of P. thyroides, but without side cusps on any of the 

 teeth. 



Genitalia: "The penis sac is the conspicuous feature of the 

 system; it is longer than the oviduct and almost as stout, of 

 about equal size throughout; it has the entrance of the vas 

 deferensand the retractor muscle at its blunt apex. The geni- 

 tal bladder is small, lengthened oval, with a long, slender duct. 

 The prostate is narrow, stout, prominent, cord-like. The vas 

 deferens is large. The other organs present no peculiar fea- 

 tures." (W. G. Binney.) 



Distribution: .Western Pennsylvania to Minnesota, south 

 to Wyandotte, Kan., Jackson County, Alabama, and Sea Is- 

 lands of Georgia. (Pilsbry.) 



Geological distribution: Pleistocene; Loess. 



Habitat: Found in moist woods under logs and debris of 

 all kinds. 



Remarks: Unless care is taken this species will be con- 

 founded with small forms of thyroides. Indeed, it has much 

 the aspect of the form known as bucculenta. The aperture in 

 clausa is always larger (in comparison to its size) and rounder 

 than in thyroides, and the shell is always more globose and there 

 is never a tooth on the parietal wall. The animal is very rapid 

 in movement, is most inquisitive, and very readily crawls over 

 the hand. It is a most uniform species, showing almost no va- 

 riation. The specimens from Joliet are unusually large and 

 fine. The species is not very common, except in the region 

 around Joliet, and it is confined to the southern and western 

 regions. 



59. Polygyra pennsylvanica Green, pi. xxix, fig. 3. 



Helix Pennsylvanica GREEN. Contr. to Macl. Lye., Nos. 1, 8, 1827. 



Shell: Obtusely conical, elevated, imperforate; surface 

 sculpture as in clausa; color light yellowish, straw or dark horn ; 

 nuclear whorls smooth; periphery rounded; sutures well im- 



