CYLICHNA. 417 



being of the same length, make a broad wedge, which 

 probably serves for probing the muddy sand in quest of 

 prey, like the snout of a pig grubbing for earthworms. 

 The apex of specimens from tenacious mud in Loch 

 Fyne and Shetland is coated with a thick and prominent 

 crust, having the appearance of a blunt spire ; this may 

 be owing to an accumulation in that part of faeces and 

 slime mixed with fine sand and mud, which had been 

 trailed along in the progress of the animal. 



It is the Bulla Oliva of Gmelin, B. cylmdrica of 

 Bruguiere, Pulteney, and Donovan (not of Chemnitz), 



B. convoluta of Brocchi, and Cylindrella alba of Swain- 

 son ; the young is the Bulla pro duct a of Brown, and 

 Bullina producta of Macgillivray. The Bulla cylin- 

 dracea of Da Costa is Marginella pallida, a common 

 West-Indian shell. 



5. C. ALBA^, Brown. 



Volv'aria alba, Brown, 111. Conch. G. B. & I. p. 3, pi. xix. f. 43-44. 



BoDi' clear white, with a faint tinge of fleshcolour on the 

 upper part : mantle thick, extending as a prominent Ibid or 

 process at each extremity of the shell : head thick, bilobed in 

 front : tentacles forming an entire and rather short disk in ex- 

 tension or continuation of the head, and folded back over the 

 front of the shell : eyes, none perceptible : foot lozenge-shaped, 

 short, bluntly rounded ill front, and ojoposed to the head (so as 

 to make together a blunt wedge), expanded and round(;d 

 behind, with an angidar lobe on each side in that part : 

 [odontopliore, rhachis small, compressed, erect, broader above, 

 wdth the cutting-point slightly produced and jagged ; uncini (J, 

 the first by far the largest and having the base extended on 

 each side, with the cutting-point strong, bent inwards, and 

 jagged or notched on the inner side, the others minute and 

 shaped like curved claws (Loven) :] gizzard like that of 



C. cylindmcea ; but the plates in the present species are 

 oblong, thicker, gibbous (instead of rounded) on the upper 

 side, witli a boss in the centre, and more convex beneath. 



* White. 



T 5 



