Pvn H,i I'UitlS

two species.
PECTEN. 69
I have never seen an intermediate form,
although I have examined many hundred specimens of
P. striatus and about fifty of P. Testce with a view to the
comparison. The present species has some of the sculpture
of P. tigrinus and the shape of P. striatus. The
colouring of P. Testce is more bright
and vivid than that
of the other two. Some specimens are perfect gems.
Mediterranean examples are usually much smaller than
those from the North Atlantic, although
I have seen
several of a tolerable size which were collected by S r .
Costa at Naples. Mr. Claries specimen from Exmouth,
and I am
in my collection, was mixed with P. tigrinus ;
rather surprised that his habit of close observation did
not enable him to separate them.
It is probably the P. incomparabilis and P. vitreus
of Risso; but his love of species-making seems to
have been so inveterate, and his collection is in such
a deplorable state of confusion, that it is almost hopeless
to attempt any identification of his names. The P.
vitreus of Chemnitz is quite a different species, as Phi-
lippi has wr ell observed.
7. P. stria'tus*, Muller.
P. striatus, Mull. Zool. Dan. Prodr. p. 248, no. 2994 ; P. & H. ii. p. 281,
pi. Ii. f. 1-4, and (animal) pi. S. f. 2.
Body whitish, irregularly streaked lengthwise with opaque
white lines : mantle edged with white and having an outer
fringe of extensile white cirri : ocelli 25 in number, blueblack
with crimson centres ; behind them is an inner fringe of
short white cirri :
gills also furnished with 20 reddish-brown
ocelli, each of which surmounts the crest of a leaflet.
Shell resembling that of P. Testce in shape;
but it is rather
larger, thinner, and more fragile, and the sculpture (especially
of the upper valve) is very different. In the present species it
* Striate.