THE NATURAL HISTORY SURVEY. 221 



very rapidly enlarging, not much expanded, the last whorl over 

 twice the size of the others combined; spire very short, acute- 

 conic; sutures very heavily impressed; aperture long-ovate, 

 narrow, straight, wider below than above the center, where it 

 rapidly narrows to an acute point; the aperture occupies from 

 two-thirds to three-fourths the length of the entire shell and is 

 somewhat patulous; when the shell is viewed from below, all 

 the volutions may be seen within the aperture; peristome thin, 

 simple, terminations widely separated; columella simple; a 

 view from the side shows the shell to be more or less cone- 

 shaped. 



Length, 19.50; width, 9.00; aperture length, 14.00; wide, 7.00 mill. (6891.) 

 16.50; " 8.00; " " 12.00; " 6.50 " (9699.) 



12.00; " 6.50; " " 8.50; " 5.00 " (10124.) 



Animal: Generally whitish or amber colored, the upper 

 part of the body covered with minute brownish or blackish 

 dots arranged in clusters; there is a black line on the upper 

 part, which extends from the ends of the eye-peduncles, along 

 the sides of the neck to the shell; eye-peduncles short, thick, 

 not much tapering, the eyes situated on bulb-shaped swellings 

 at the tips; tentacles very short, conical; foot long and narrow, 

 truncate before and pointed behind, 9.50 mill, long, and 2.00 

 mill, wide; the head is distinct and separated from the body by 

 a neck; respiratory orifice on the right side of the shell near 

 the peristome, about a fourth of the distance between the an- 

 terior and posterior borders of the latter. Heart situated to 

 the left of the aperture, midway between upper and lower mar- 

 gins; pulsations somewhat irregular, one hundred and fifty to 

 one hundred and fifty-five per minute. 



Jaw: Arched, ends blunt; cutting edge with a central 

 projection and three smaller swellings on each side; anterior 

 surface smooth. The usual superior appendage is present. 

 A specimen examined by Morse had the anterior surface cut 

 up into several vertical furrows which modified the lower mar- 

 gin. Binney found a jaw with smooth anterior surface and 

 strong median projection (Fig. 56, J). 



Radula formula: V+f+l+i+l+f+V (60-1-60); cen- 

 tral tooth longer than wide, the lower part of the base of 

 attachment produced at the outer corners, reflected portion 

 tricuspid, the central cusp very long but not reaching the 

 lower margin of the base of attachment, and the side cusps 

 small; lateral teeth almost as wide as long, similar to central, 



