PAXOP./EA. 163 



the foot is very small; the tube is of large diameter, and, 

 when fully extended, is 7 inches long, fleshy, and covered with 

 a dark epidermis, which gives it as rugose an aspect when 

 nnder contraction, as that organ in My a truncata ; it forms 

 near the extremity the two siphonal orifices, which are scarcely 

 separated, the upper or anal one being rather the shortest; 

 they are both furnished with short, simple, white cirrhi, not 

 digitated or fimbriated as in some of the Mya. The branchiae 

 are extensive, but not deep, well arcuated on the body, the 

 upper plate lapping only on half the surface of the lower one ; 

 they are very long, and after quitting the body, gradually taper, 

 becoming linear, and are prolonged nearly to the extremity of 

 the siphonal apparatus, terminating in acute points, and cannot 

 be much less than 6 inches in length ; the colour on the body 

 portion is light drab, rather sparingly aspersed with minute 

 bistre-coloured points ; the pectinations on the part coasting 

 the body are visible, but not strong ; as they advance they 

 become coarsely crimped or wrinkled. The anal and siphonal 

 issues are not separated their whole length from the extremities 

 to the body, by an impermeable wall, as in the Pholades, but 

 only for an inch at the terminations, and then debouche into 

 the main tube; the branchiae in Gastrochaena and Saocicava 

 are of the same linear complexion, and similarly deposited in 

 the main tube; the palpi are long, slender, delicate, pointed 

 and triangular, united around the mouth, pale drab, very finely 

 pectinated without, and smoother within. The body is of a 

 thick oval mould, pale pinkish-drab, and from its centre a 

 very small byssal-grooved foot proceeds, which, as far as could 

 be judged, would, when exserted, produce a subcylindrical one, 

 like that of Saxicava and Gastroch&na ; it is certainly less 

 linguiform than in My a, which also differs from it in having 

 no byssal groove. The liver, as usual, is green. In other 

 respects there is nothing peculiar in the aspect of the animal. 

 There was no byssus in the groove of the heel of the foot. 



This species has not yet been found on our southern shores ; 

 it has, however, been reported from Scarborough. The above 

 remarks are from the examination of an adult animal sent us 



M 2 



