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Art. XVI II. — Description of a new species of Peckii, from 
the Outer Hebrides. By Mr W. Macgillivuay, Correspond- 
ing Member of the Wernerian Natural History Society. 
In a collection of shells transmitted to me from Harris, by a 
young man of that island, I found a beautiful species of Pecten, 
which, after a diligent sjearch in various works on conchology, I 
consider myself authorised to pronounce non-descript. It occurs 
at the Island of Scalpay, and more abundantly at a place on the 
east coast of Harris, called Miavag-a-chuain. Its description is 
as follows : 
Shell orbicular, in }^oung specimens rotundato-oblong, subm- 
quivalve, the upper valve a little less convex than the under, 
thin, fragile, diaphanous, with 46 subcompressed, rounded ribs, 
sparsely echinated with transverse delicate laminae. Auricles 
very unequal : the longest of the upper valve with 7 divergent 
echinated ribs ; and joined to the shell by a broad convex la- 
minated rib ; that of the lower valve broader, with 8 similarly 
echinated ribs ; the smaller auricles also ribbed and echinated. 
Eight delicate marginal teeth on the upper valve close upon the 
auricle, and the series continued into the auricular groove. In- 
terstices of the ribs marked with very fine transverse bent ridges 
and grooves, scarcely visible to the unassisted eye. Colour pure 
white. The dimensions of the largest specimen which I pos- 
sess are as follows: length 3 inches, breadth length of au- 
ricular margin 1| inch. 
In respect to its general form and echinations, it approaches to 
P. varius , but it differs in the following particulars : P. varius 
is a thick opaque shell, with its transverse laminae coarse ; this is 
a very thin diaphanous on?, with the transverse laminae exceed- 
ingly delicate : in P. varius the ribs are 32, and marked with 
coarse irregular echinations ; in this they are invariably 46, ex- 
ceedingly delicate in themselves, and regular in their echina- 
tions ; in P . varius the colour is various, sometimes yel- 
lowish white, yellow, brown, or mottled, or variegated, but never 
pure white ; in this, it is white, so pure, that the inner surface 
has even a tint of blue. The differences in short are much 
greater than those between Venus pullastra , and decussata , 
Cytherea exoleta and concentrica. 
I propose giving it the name of Pecten niveas , Snowy Scallop. 
