MYA. 1(57 



even the excuse of an extraordinary number of species as a 

 sort of palliation for its constitution. 



M. OBLONGA, nobis. 



Lutraria oblonga, Chemnitz. 



-, Brit. Moll. i. p. 374, pi. 13. f. 1. 

 Mactra Mans, Mont, et Auct. 



Animal oblong, tolerably thick, very pale yellow, with the 

 mantle closed, except a large anterior fissure for the foot ; it 

 is also produced into a large, rugose when contracted, sheath, 

 but not so much so as in M. truncata. The ground colour is 

 white, but covered with a brown epidermis, which also is 

 deposited on the ventral regions of the mantle ; the common 

 sheath, containing the two siphons, can be greatly inflated, 

 and is often extended twice the length of the shell ; it only 

 just bifurcates at the terminus, showing the orifices of the 

 siphons ; the anal is of much less calibre than the branchial, 

 and encircled by 30-40 short, fine, simple, red-brown cirrhi ; 

 the branchial has about the same number, of similar colour, 

 half of which are stronger and longer than the others, being 

 fimbriated on each side ; the remainder are interstitial. The 

 foot is large, rather fleshy and linguiform, white, with a tinge 

 of pale brown, and without a byssal groove. On each side 

 there are a pair of branchiae and palpi ; the former are narrow, 

 not strictly linear ; the upper one is not so deep as the under 

 one anteally, but posteally they are much of the same dimen- 

 sions, having their points deposited in the branchial siphon ; 

 they are pale drab, with the transverse vessels of the circulation 

 well marked on both sides. The palpi are very large, triangular, 

 pointed, of very thin membranous texture, pale brown, and 

 elegantly aspersed with minute red-brown points; the two 

 pairs are united by plain labia passing around the mouth. 



We have taken this species at Exmouth alive : though very 

 large valves are taken in the dredge, and continually cast on 

 shore, it is singularly scarce, probably inhabiting the littoral 

 limits, and lodged so deep as to escape detection and the action 

 of the dredge. The above is taken from a fine 4-inch spe- 

 cimen sent me to Bath, this 21st January, 1851, having been 



