60 



PROCEEDINGS OF THE ACADEMY OF 



Measurements of genitalia in millimeters. 



[Feb.. 



In the alcoholic specimen from Nine-mile, the sole is tripartite by 

 faint longitudinal impressed lines, with a median groove due to partial 

 folding of the foot. There are transverse lines as shown in pi. Ill, 

 figs. 3 and 6. The granulation above is fine and pebble-like as usual 

 in Sonorella. The oesophagus is short, expanding into a large crop, 

 on which the loose and open salivary glands lie. The liver is reddish 

 purple. The buccal retractor and left ocular retractor are united in 

 their posterior third, the tail and right ocular retractors being free 

 to their common insertion. The lung is like that of Sonorella optata. 



In the specimens from Stations 3, 4 and 5, no longitudinal impressed 

 lines could be traced on the sole. 



The jaw varies a good deal; a specimen from the type lot has six 

 wide ribs. From Station 4 and Nine-mile the jaw has eight narrow- 

 ribs. 



All of the radulse examined agree in having decidedly fewer teeth 

 in a transverse row than S. hachitana flora or S. optata. 



Sonorella optata n. sp. PI. I, figs. 6-12, 17-19. 



The shell is umbilicate, umbilicus slightly less than one-seventh the 

 diameter, similar to S. hachitana. Pale brown, fading to whitish 

 around the umbilicus, encircled by a rather wide dark chestnut band 

 above the periphery, bordered above and below with paler, whitish 

 bands. The spire is low conic. Whorls 5 \, slowly increasing to the 

 last, which is much wider, and descends deeply in front. The embryonic 

 shell consists of H whorls. The first half whorl has radial wrinkles, 

 and begins in a smooth tip ; then a small areolate area follows, after 

 which there are curved, forwardly descending delicate threads reaching 

 the suture below, but weak or obsolete on the summit of the whorl, 

 which is irregularly roughened; there are also some forwardly ascending 

 threads in places. The first neanic whorl has sculpture of slight 

 growth ripples and an indistinct roughening or punctation. Subse- 



