1 82 OYSTERS, AND ALL ABOUT THEM, 



her, blue-black 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 consists of numerous fine ribs, which 

 radiate from the beaks to the front and side margins, and 

 have their crests thickly set with short vaulted spines or 

 prickles ; besides these riblets, the surface is closely 

 covered with extremely minute and irregular longitudinal 

 striae, which are raised and divaricate or become forked, 

 but they are never reticulated or punctured, as in P. Testce. 

 The colour is of a more sombre hue. The left ear of the 

 upper valve hangs down much lower, and is nearly entire 

 instead of being deeply notched, as in that species ; and 

 the byssal sinus is consequently larger. Length 0*725, 

 breadth cry. 



HABITAT : Plymouth (Jordan) ; F. Scandinavia and 

 Italy ; ! E. Mediterranean and Adriatic ; ! seas of Shetland, 

 Scotland ; north-eastern coasts of England ; north, east, 

 south, and west of Ireland ; Isle of Man, and Scilly ; in 

 12-90 fathoms, hard ground. Morch has procured it from 

 the Faroe Isles, and Danielssen from West Finmark. It 

 also inhabits other parts of the Scandinavian coast. 

 McAndrew has dredged it in Vigo Bay, at a depth of 1 5 

 fathoms, and Philippi describes it as a Calabrian fossil, 

 under the name of P. rimulosus. The shell is sometimes 

 distorted. The pallial ocelli or eyelets are of unequal size 

 and irregularly placed ; they gleam with an opaline lustre. 

 Living specimens which I dredged in 85 fathoms had the 



