42 
without the slit. The shell was well worn, and therefore 
probably destitute of marks which in a living slate* 
may characterize it ; but it differs so far from Pennant':* 
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. loO. Mont. Test. Brit., vol. 2, p. 477. Flem- 
Brit. An. p. 280. 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, * 
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 
sea-weeds. 
* P. VIRGINEA. P. Parva. Turt. Lin. Mont. Test. 
Brit., vol. 2, p. 480. I*. V. Flem. Brit. An., p. 287- 
Common, on rocks near low-water mark. 
P. CLEALANDI. Flem. Bril. An., p. 287. Length about 
three tenths of an inch, and not quite so wide : the fori* 1 
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. ID, fig. 8. “ An opaquo oval shell, of a glossy yello« r 
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 sip' 
gular species at Falmouth in Cornwall ; and another, l£l 
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 Montagu’s account of this obscui’ 9 
species. I have met with a single specimen of wl* at 
perhaps may be the same species : leDgth live twentieth® 
of an inch, breadth three twentieths; oval, regular, tl* e 
umbo about the middle of the length and breadth; f£> rBl 
depressed. The texture somewhat flexible ; margin even, 
hut a little waved, not in its substance, but moulded by tl,e 
shell to which it was attached. Colour reddish yello' v ' 
It was fixed on the shell of a pinna, after the manner 0 
Pileopsis Hungarians, and like that shell seems not to b 
accustomed to change its place. 
r lhe form and habits of the shell here described seenj 
intimate an affinity to the genus Umbrella : (characterized a 
