142 PYRAMIDELLIDiE. 



Habitat : Coralline zone,12-50f., Guernsey (J. G. J.); 

 Fowey (Barlee), Exmouth (Clark), Hebrides (J. G. J.), 

 Aberdeenshire (Dawson), Shetland (Barlee and J. G. J.); 

 it is both local and rare. I am not aware of any geo- 

 logical or foreign locality. 



This species differs from 0. insculpta in being more 

 spindle-shaped than cylindrical, of a thinner texture, 

 quite smooth instead of spirally striated, having fewer 

 whorls (the last being disproportionately large), with 

 a more oblique suture, and in the umbilicus being nar- 

 row and inconspicuous. It is certainly not the young 

 of 0. obliqua, as Forbes and Hanley supposed. The 

 present species is in every state of growth more slender 

 (in consequence of the whorls not being so tumid) ; nor 

 is it ever striated, like that species ; the umbilicus also 

 is smaller, and the nucleus of the spire less prominent. 

 Mr. Clark's description of the animal of 0. obliqua was 

 taken from a specimen of O. diaphana, which is now in 

 the fine collection of Mr. Leckenby at Scarborough. 



18. O. obli'qua*, Alder. 



0. ? obliqua, Alder in Ann. & Mag. N. H. xiii. p. 327, pi. viii. f. 12. 0. 

 obliqua, F. & H. iii. p. 291, pi. xcvi. f. 1. 



Body clear white, with a slightly frosted appearance : man- 

 tit occasionally forming a small conduit or fold at the upper 

 angle of the aperture of the shell : snout short, cloven as far 

 as the eyes, having the segments curved to the right and left : 

 tentacles short, bevelled, not broad, tapering to a fine point, 

 and having small white inflated tips ; they are carried in front 

 of the head with an angular divergence of about 75° : eyes close 

 together, at the united internal bases of the tentacles : foot 

 short, concave in front, slightly auricled, terminating obtusely 

 behind. (Clark.) 



Shell shaped like that of a miniature Limnaia of the stag- 

 nalis type, extremely thin, transparent, and glossy : sculpture, 



* Slanting. 



