PECTEN. 63 



grooved as in other ribbed species : muscular scars rather 

 distinct. L. 1-625. B. 1-475. 



Yar. 1. alba. Shell of a milk-white colour. 



Var. 2. Dumasii. Shell smaller and more solid, longer in 

 proportion to its breadth ; upper valve less convex than the 

 lower one and sometimes quite flat or even slightly concave : 

 sculpture coarse, with 3-10 sharp ribs : ears often unequal, 

 those on the byssal side smaller than the opposite pair. P. 

 Dumasii, Payr. Cat. Moll. Corse, p. 75, pi. ii. f. 6, 7. 



HABITAT : Rather plentiful in Loch Fyne, and gene- 

 rally distributed over our northern seas, and southward 

 as far as the Northumberland coast, in 20-90 fathoms, 

 rough ground. Var. 1. Loch Fyne and Shetland (Bar- 

 lee). Var. 2. Hebrides and Shetland. This species is 

 fossil in the Clyde basin, and in other glacial deposits in 

 Scotland as well as Norway. It ranges from Finmark 

 to the ^Egean, but it appears not to be so common in 

 the south as in the north. The variety Dumasii occurs 

 in the upper miocene strata near Antibes. 



P. septemradiatus was added to the British fauna by 

 the late Capt. Brown in 1835. It is remarkable that 

 such a handsome and by no means small shell should 

 have previously escaped the notice of Laskey, Fleming, 

 Macgillivray, and others of our northern conchologists. 

 This can scarcely be accounted for by the dredge not 

 having been used in those days, because specimens are 

 usually procured from fishermen. They are frequently 

 caught in the herring-nets, when disturbed on their 

 feeding- grounds and swimming or flitting about. I 

 am not aware that the animal has ever been described ; 

 and I have unfortunately missed the opportunity of 

 observing it. Asbjornsen mentions his having taken 

 specimens in the beginning of May, which were full of a 

 milky fluid. The shell is extremely variable in respect 

 of shape and the number of ribs, as well as of the pro- 



