GALLOMMA. 189 



intersection the angles are slightly nodulous : colour snow- 

 white : epidermis not visible and apparently replaced by the 

 pallial membrane : margins obliquely truncate and wedge- 

 shaped at the anterior side, the end of which is rounded, gently 

 curved in front for the entire breadth of the shell, with an 

 extremely long and wide ventral gape, more decidedly trun- 

 cate and somewhat longer at the posterior side, which is also 

 wedge-shaped and has a rounded end : heals slightly pro- 

 minent, and appearing like small nipples, placed nearer the 

 anterior side : hinge-line nearly straight, occupying more than 

 half the breadth of the shell : cartilage oval, yellowish-brown, 

 lying close to the beaks on the posterior side : hinge-plate in- 

 curved, somewhat thickened, terminating on the anterior side 

 in an obtuse angle, and merging in the slope on the other side : 

 inside pearl-white and glossy, with the edges finely crenulated 

 by the projection of the longitudinal ribs, and slightly grooved 

 on each side below the hinge-plate : muscular scars oval. 

 L. 0-2. B. 0-4. 



Habitat : Rocky and stony ground, from low- water 

 mark to 20 fathoms, on some of our southern shores ; 

 but it is very local. It is not uncommon in the little 

 island of Herm, where it was probably discovered by 

 Dr. Turton ; single valves are not unfrequently dredged 

 off Guernsey ; Mr. Clark obtained it alive in the same 

 way off Exmouth ; and Mr. W. Thompson has taken it 

 in Eschar a foliacea, thrown up on the beach at Wey- 

 mouth after a storm. The single valve mentioned by 

 Turton in his original description, on the authority of 

 Dr. Goodall, was formerly in the collection of Mr. George 

 Humphreys, and is said to have come from Ireland. It 

 is now in my cabinet. Cailliaud has found it on the 

 coast of Brittany, D'Orbigny at Noirmoutiers in La 

 Vendee, M f Andrew in Vigo Bay j and several others have 

 noticed it as inhabiting the Mediterranean, from the 

 Gulf of Lyons to Sicily, as well as the Adriatic. The 

 only occurrence of it in a fossil state was observed by 

 me at Biot near Antibes, where I found a single valve 



