394 MARSHALL: ADDITIONS TO “ BRITISH CONCHOLOGY.” 
Pholas dactylus L—La Rocque, Jersey, a few feet below 
high water mark, dead shells only zz sz¢u. These must be 
considered sub-fossil, as many years must have elapsed and 
great changes have taken place in the coast-line——either by 
a raising of the land or an encroachment of the sea—since 
P. dactylus could live in what is now nearly high-water 
mark. 
Var. gracilis Jeff_—Torbay. This is a difficult species to 
procure alive, as they live lower down than the other 
Pholades, and burrow much deeper. 
P. parva Penn.—An inequivalve monstrosity is occasionally 
found having one valve larger and sometimes broader than 
the other. The depauperated form (var. guadrangula) has 
been found semi-fossil in hard clay off Gosport by Lord 
Walsingham, and similar valves are in the National Col- 
lection, but without locality. 
P. crispata L.—Hoylake (Webster). 
Very small valves somewhat resemble those of Zeredo. 
Specimens from the Belfast clays are of extraordinary: 
dimensions; I have some valves 44 in. broad by 2} in. 
long, and a perfect specimen would be 8 in. in girth. 
Pholadidea papyracea Turt.—Pullaheeny, Mayo, a valve 
(Miss Warren)! Weymouth Bay (Dodd, jde Fowler) ; 
Gwyllyn Vase, Falmouth ; Alum Bay, Isle of Wight. 
Var. aborta Jeff.—-Torbay, in red sandstone, with the type. 
A remarkable monstrosity from Torbay has the smooth 
area which bulges out on the anterior part of the adult 
shell, continued right round the margins. 
This lives as deep as Pholas dactylus, and its burrows 
are uncovered only at very low spring tides, and for a short 
time only. ‘The reefs in which they occur on the South 
Devon coast are generally divided into three layers— 
Tapes pullastra var. perforans and Saxicave occupy the 
first or top layer, Pholas parva the middle one, and Phola- 
J.C., viit., July 1897 
