42 



without the slit. The shell was well worn, and therefore 

 probably destitute of marks which in a living state, 

 may characterize it ; but it differs so far from Pennant's 

 figure of P. Intorta, pi. 00, fig 1 48, as to leave no doubt 

 of its being distinct, 



* P PELLUCIDA. Turt. Lin. Pen. Brit Zo, vol. 4, 

 pi. 90, fig. 150. Mont. Test. Brit., vol. 2, p. 477. Flem. 

 Brit. An. p. 286. Common, but in its different stages of 

 growth so various, as to have led to confusion of the 

 synonyms. Montagu confounded it with P. Intorta, a 

 species which it appears, at that time he had not seen. 



* P, LEVIS. Pen.* Brit. Zo, vol. 4, pi. 90, fig. 151. Flem. 

 Brit. An., p. 287. Common, on the fronds of the larger 



* P. VIRGINEA. P. Parva. Turt. Lin. Mont. Test. 



Brit., vol. 2, p. 480. P. V. Flem. Brit. An., p. 287. 

 Common, on rocks near low-water mark. 



P. CLEALANDI. Flem. Brit. An., p. 287. Length about 

 three tenths of an inch, and not quite so wider the form 

 an irregular cone, the summit elevated, pointed, rather on 

 one side. The edge even, without longitudinal ribs, but 

 with concentric lines of growth. Colour dull white. A 

 single specimen found at Gorran. 



P. BIMACULATA. Mont. Test. Brit,, vol. 2, p. 482, 

 pi. 13, fig. 8. " An opaque oval shell, of a glossy yellow 

 colour, and perfectly smooth, with only the rudiment of a 

 vertex at the smaller end, marked by a transverse, oblong, 

 black spot; another oblong spot of the same colour near 

 the other end, placed longitudinally; the shell is convex, 

 but not much elevated. Inside concave, smooth, glossy, 

 yellow ; margin thin. Length a quarter of an inch, 

 breadth rather more than one-eighth ; height about one 

 sixteenth of an inch. We found one of this rare and sin- 

 gular species at Falmouth in Cornwall; and another, in 

 every respect the same at Milton sands, on the south coast 

 of Devon ; they were both recent and perfect shells, but 

 not alive." Such is Moutagu's account of this obscure 

 species. I have met with a single specimen of what 

 perhaps may be the same species : length five twentieths 

 of an inch, breadth three twentieths; oval, regular, the 

 umbo about the middle of the length and breadth; form 

 "depressed. The texture somewhat flexible ; margin even, 

 but a little waved, not in its substance^ but moulded by the 

 shell to which it was attached. Colour reddish yellow. 

 It was fixed on the shell of a pinna, after the manner of 

 Pileopsis Hungaricus, and like that shell seems not to be 

 accustomed to change its place. 

 The form and habits of the shell here described seem to 



intimate an affinity to the genus Umbrella : (characterized as 



