184 THE CHICAGO ACADEMY OF SCIENCES. 



by very fine, oblique, crowded growth lines, which disappear 

 on the large, rounded, flat nucleus; color light yellowish-horn; 

 periphery rounded; sutures deeply impressed; whorls six, nar- 

 row, rounded, very regularly increasing; spire generally ele- 

 vated, sometimes a little depressed, convex; aperture trans- 

 verse, wider than high, somewhat moon-shaped in some speci- 

 mens, contracted by the body-whorl; peristome thin, acute, 

 simple, the terminations widely separated; umbilical region 

 indented, but the umbilicus closed or minutely perforated, base 

 rounded; last whorl angular in front, the angularity becoming 

 obsolete on the latter part of the whorl. 



Greater diameter, 2.25; lesser, 2.00; height, 1.75 mill. (10648.) 

 2.75; " 2.25; " 1.75 " (10647.) 

 2.QO; " 2.50; " 2.00 " (10107.) 

 8.00; " 2.50; " 2.50 " (12295.) 

 3.00; " 2.80; " 2.75 " (Coll. Jensen.) 



Animal: With a long and narrow foot, with distinct cau- 

 dal mucus pore and pedal grooves; tentacles short and blunt; 



FIG. 39. 



Teeth of EUCONULUS FULVUS Drap. (Original.) c, central tooth; 

 1, first lateral; 15, fifth perfect marginal; J, jaw. 



eye-peduncles long and tapering; color blackish on head, neck 

 and eye-peduncles, rest of body dirty white; a black stripe 

 extends from each eye-peduncle over the back to the shell. 

 When viewed dorsally the animal is almost hidden by the shell, 

 which is large in comparison with the foot. Heart situated 

 near the umbilical region, pulsations variable, ranging from 

 one hundred and thirty-five to one hundred and fifty per minute. 

 As in all mollusks, warmth accelerates the action of the heart. 

 A specimen measuring 4 mill, in length was almost jet black 

 in color. 



Jaw: Strongly arched, very wide in the middle and taper- 

 ing at either end, which is rather pointed; margins smooth, no 



