250 
Sow. Th. Pecten. f. 47.—P. Vitrmus. var Chemnitz. 
J. 637. 6. Equivalve, suboval, thin, with radiating 
strize armed with elevated minutely prickly dots; ears 
unequal, the anterior small; the posterior large and in 
one valve strongly emarginated ; pale yellow clouded 
with red. 0,8...0,9. Oban. 
P.Nivreps Macgillivray in Edin. Phil. J—Sow. Th. 
Monog. Pect. f. 223, 4.—Oval white, rather thin, the 
left valve very slightly the larger; ears unequal, the 
posterior rather large; ribs fourty, smooth, quadrate 
armed with distant erect acute spines; interstices flat. 
13...1,7. Bears a strong resemblance to Varius. 
Scotland. 
P. IsaBELLaA Macgil. Aber. p. 225. Rounded- 
ovate, subequivalve, little convex, with twenty four 
slender compressed rounded ribs having very numerous 
elevated thin edged lamelle rising towards the margin 
into triangular compressed pointed spines, the grooves 
with transverse scalar lamellze not extending over the 
ridges; ears very unequal, with radiating sulci trans- 
verse lamellee and spines: margin of the upper valve 
under the auricular sinus with four free curved conical 
spinelets, of which a series is continued to the smooth 
and glossy umbo ; white, lower valve tinged with pink, 
Aberdeen, 0,23..,.0,27. 
