“tal 
152 THE CHICAGO ACADEMY OF SCIENCES. 
Shell: Depressed globose, rather solid, imperforate; sur- 
face covered with numerous fine, oblique striz which are obso- 
lete on the apical whorls, and the whorls are encircled by very 
numerous fine, wavy, spiral lines, which give the surface a lat- 
ticed aspect under the glass; color yellowish-brown, sometimes 
darker, without bands; periphery rounded; sutures much im- 
pressed; whorls five to six, rounded, regularly increasing; spire 
but littleelevated; aperture lunate, contracted by the peristome; 
peristome widely reflected, white, flattened, with sometimes a 
small callosity near the columella, which is nearly straight; 
umbilicus covered in the adult shell by the reflection of the 
peristome, which formsa spreading callus; base of shell convex. 
Greater diameter, 32.00; lesser, 26.00; height, 19.00 mill. (7972.) 
is BOLD s 2 HSS AE aoe 18.00 “  (8091.) 
Animal: With a long foot which is wide and spreading at 
the base, and slopes up to meet the rounded body and neck; 
posterior extremity of foot flattened and spreading, acutely 
pointed, and rising to meet a central dorsal keel. Color yel- 
lowish-brown, with a dark stripe extending down the center of 
the neck and head to the shell; tentacles and eye-peduncles 
almost black; sometimes darker along sides of body; the 
animal is sometimes whitish or cream-colored, and may be 
almost black. Eye-peduncles very long, bearing the black 
eyes; tentacles short and cylindrical, tubercles on the back very 
prominent and arranged longitudinally. The foot of a large 
specimen measured 60 mill.in length and 14 mill. in width, and 
the eye-peduncles measured 13 mill. in length. The heart 
pulsations are as follows: 50-56-61 (adult); 69 (half-grown); 
106 (very young); 48 (animal dormant). 
Radula formula: 42+14$+19+44+19+%+9 (44-—1-—44) 
(sometimes 45—1—45). Central tooth with a long and narrow 
base of attachment, the lower outer corners expanded and the 
base excavated; reflection reaching below the margin of the 
base of attachment, with the cusps similar to those of ¢”dentata, 
but narrower; lateral teeth similar to central; marginal teeth 
at first like lateral teeth, but soon (28) the inner cusp becomes 
bifid, the cusp becomes wider (30—35) and extends far below 
the base ofattachment. Thirty-eight is a marginal of abnormal 
form; one row had all of the thirty-eighth teeth of this form 
(Fig. 20). There are over 120 rows of teeth. 
Jaw: Similar to that of thyroides, but very arcuate and with 
a ; 
Bi a Td eae 
