JEFFREYSIA. OO 



which resemble tentacles but are close together : tentacles cy- 

 lindrical, rather short, with blunt tips : eyes large, round, and 

 sessile, placed far behind the tentacles : foot lanceolate, short, 

 deeply cloven and bilobed in front, bluntly pointed or almost 

 round behind. 



Shell globosely conical (like that of Valvata pischioJis), ex- 

 tremely thin, transparent, highly glossy, and partially irides- 

 cent : sculpture the same as in the preceding two species : colour 

 whitish when the shell is empty, dark homcolour when con- 

 taining the animal or its dried remains : sj^ire short and com- 

 pressed ; apex blunt : whorls 3|, very tumid, rapidly enlarging ; 

 the last occupies three-fourths of the spire : suture remarkably 

 deep : mouth roundish- oval, somewhat detached, half the length 

 of the spire : outer lij) sharp and thin, considerably incurved 

 above, sHghtly expanding and rounded below : inner lip sepa- 

 rated from the pillar to a greater extent than in either of the 

 other species, so as to make the peristome more distinct : 

 umbilicus rather narrow but deep : operculum shorter and 

 more oval compared with that of the other species ; the marks 

 of growth are also more conspicuous, and evidently show a 

 concentric arrangement. L. <>0.5. B. 0-065. 



^Monstr. Partly scalariform, in consequence of the suture 

 being excavated and becoming much broader near the mouth. 



Habitat : On Laminarice at Croidiu Islaud_, iu Skye 

 (Barlee), and, with /. diaphana and /. opciUna, at the 

 Whalsey Skerries (Barlee and J. G. J.) ; rather plentifnl. 



The tentacular processes of the snout in this species are 

 much smaller and further apart than the true tentacles. 

 In /. opalina the snout is very prominent, and quite 

 distinct from the second pair of tentacles. In both 

 species the hinder tentacles are usually borne at a right 

 angle to the axis of the sheU, and the other processes 

 in fi'ont diverge at an angle of about 45^. 



