210 RETUSA. 



with a minute furrow behind. Alt. 0*092 in., diam. 0'046. Breadth 

 of mouth at same place, 0*005 inch (Wats.). 



Madeira ; Tenerife, Canaries, 78 fms. 



Utriculus tornatus WATS., J. L. S. L., xvii, p. 335 ; Chall. Rep. 

 Gastr., p. 651, pi. 48, f. 10. 



This is a species extremely abundant at Madeira, where I dredged 

 many thousand specimens. They vary somewhat in the relation of 

 length and breadth, and still more in the form of the crown, which 

 is sometimes flat and broadish, with an impressed suture, at other 

 times narrow, with a small, deep opening and a very depressed apex, 

 the sutures in these circumstances being out of sight. I should ex- 

 pect to find this species among Mediterranean shells, but have not 

 ; been able to identify it. It is not unlike Utriculus mamillatus (Phil.), 

 but is stumpier and not so cylindrical, being broader in front and 

 more tapering backwards; its papillary apex, too, is much smaller 

 and more sunken into the crown of the shell than it is in that spe- 

 cies : the whole crown is very much like that of Utriculus trunca- 

 tulus (Brug.), but the characteristic constriction and sculpture of 

 that species are wanting ( Wats.). 



R. UMBILICATA Montagu. PI. 29, figs. 11, 12, 13, 14. 



Shell oblong, not so much attenuated behind as R. nitidula, 

 more solid, nearly opaque, and glossy but not prismatic; sculpture 

 slight and sometimes wavy spiral striae or impressed lines, which 

 vary in strength and remoteness on the body, and are more or less 

 close-set near the base ; they are visible in fresh specimens by means 

 of a low magnifying power, but are not easily observable in rubbed 

 specimens picked out of drift sand ; epidermis brownish-yellow, lia- 

 ble to peel off; color creamy, becoming bleached and white in dead 

 shells ; mouth somewhat open at the top, contracted and narrow in 

 the middle, pear-shaped and wide at the base, where it is expanded 

 and rounded ; outer lip gently curved ; the upper part is obliquely 

 truncated, but it does not project so far beyond the apex or crown 

 as in R. nitidula ; apex twisted and somewhat contracted, en- 

 circled by a solid white rim (" periomphalus," Loven), and exhibit- 

 ing a perforation in the center like that of C. nitidula ; inner lip as 

 in R. nitidula ; pillar short and thick, furnished with a rather 

 strong tooth-like fold near the base ; it has a sharp curve to the left. 



Alt. 2-5, diam 1-2 mill. 



Norway to Gibraltar ; Mediterranean and Adriatic Seas. 



