THE, NATURAL HISTORY SURVEY. 153 
ten ribs of somewhat unequal size. The ends of the jaw are 
smooth on their anterior surface. 
Genittaha: ‘The penis sacis stout,rather short, cylindrical, 
with a median prepuce; it receives the vas deferens at its sum- 
mit; the retractor muscle is inserted on the vas deferens near 
its junction with the penis sac; the genital bladder is long, 
stout, blunt at itssummit; its duct is very narrow at its entrance 
into the bladder fora short portion of its course, then becomes 
suddenly expanded into very much the shape and still greater 
size of the bladder.”* This peculiar arrangement of the geni- 
tal bladder and duct distinguishes albolabris from all related 
species. 
Fic. 20. 
Radula of POLYGYRA ALBOLABRIS Say. (Original.) c, central tooth; 
1, first lateral; 12, twelfth lateral; 24, 28, first marginals; 30,35, outer mar- 
ginals; 38, abnormal marginal. 
Distribution; Canada, Eastern and Central United States. 
Geological distribution: Pleistocene; Loess. 
Habitat: Found under and about old logs in open wood- 
lands, and in wet weather crawling over the vegetation. 
Remarks: Distinguished by its large size, imperforate 
base, and white lip. This is our largest and handsomest snail, 
and is found only in the southern and western regions. The 
animal is slow in movement, but not at all timid, readily allow- 
ing itself to be handled without withdrawing into its shell. 
When crawling up the side of a glass jar the shell is so heayy 
that it hangs almost to the extremity of the foot. The eye- 
peduncles are pointed straight ahead during locomotion, the 
shell is carried almost flat, and the tentacles are directed 
straight downwards. When eating, the head is drawn partly 
*W.G. Binney, Man. Amer. Land Shells, p, 200. 
