MARSHALI.: ADDITIONS TO ‘ BRITISH CONCHOLOGY.” 371 
not more so than in the type. The sculpture is usually, 
though not always, coarsely impressed concentric striz. 
It resembles P. costu/ata, and Dr. Jeffreys must have made 
a lapsus penne when he wrote that it ‘resembles Ga/eomma 
turtont in shape.” From Sutherlandshire (Baillie) !. Minch 
off Barra, 35 f. (Somerville and J.T.M.). 
P. costulata Turt.—Scilly (Smart and others) ; Barnasset 
(Somerville and J.'f.M.); Herm Island, living in sand at 
low water. It seems to have escaped notice that this 
species is inequivalve. The very young cannot be distin- 
guished from those of P. ¢e/dinella. My finest are from 
Guernsey, and are nearly r} inches in breadth. 
P. ferroensis Chem.— Guernsey Harbour, rare. A small 
form from Bantry Bay, collected by Mr. Bartlet Span, is 
of a uniform deep purple. 
Var. pallida n.var.—Pure white to pale yellowish white, 
without rays; epidermis fragile and of a silky texture. 
Collected at Tenby by Mr. Bartlet Span. 
P. vespertina var. lactea Jeff.—Guernsey and Herm, rare. 
The shape of the teeth in this variety is not constant, and 
should not be considered characteristic, the degree of 
‘erectness’ and ‘pointedness’ being a question of wear and 
tear. Half-grown specimens of the type exhibit the den- 
tition ascribed to this variety. 
Var. livida Jeff.cWest of Scotland. This variety does not 
depend so much on its colour as on its shape. 
Donax vittatus var. nitida Jeff.—Aberdeenshire. 
Var. truncatus Marsh. (Irish Naturalist, Jan. 1895, with fig.) 
—This variety is peculiar, so far as I am aware, to the 
south and west of Ireland. The umbonal area inside the 
valves is fretted with deep pit-marks, which I thought 
might be caused by a parasite, as in dredging the var. 
nitida on the Doggerbank many years ago (which is a 
similar convex form) I found that fifty per cent. contained 
