MYA. 165 
MYA, Linneus. 
M. rruncata, Linn. et Auctorum. 
M. truncata, Brit. Moll. i. p. 163, pl.10. f. 1,2, 3; (animal) pl. H. f.1. 
Animal elongated, subcompressed; mantle pale brown, 
closed. throughout, except an anterior fissure for a moderate 
tongue-shaped, yellowish-white foot, with a byssal groove, and 
being also produced into a long brown sheath covered with a 
dark rugose epidermis, under which the skin is white ; it can 
be extended to double the length of the shell; when con- 
tracted it presents the aspect of a mass of close-set annular 
corrugations ; the sheath also contaims the anal and branchial 
siphons, which are united to their terminations, and scarcely 
appear beyond the walls of the common envelope; the former, 
besides the usual exsertile valve, has about fifteen short dirty- 
white cirrhi, with as many still shorter between them ; the lat- 
ter has twenty similar filaments, with mtermediate short ones. 
There are on each side a pair of pale brown branchiz, rather 
narrow, the upper beimg somewhat less in depth; they are 
well pectinated on both surfaces, and their points enter the 
branchial sheath, but not to near the extent of the Pholades ; 
the two pairs of palpi are large, basally broad, triangular, of 
excessive thin texture, marked with fine short brown minute 
dots, and end in a sharpish point ; they are connected toge- 
ther by labia coasting the buccal orifice, and are visibly pec- 
tinated on both sides. The liver is dorsal, granular and yel- 
lowish-green, haying the ovarium in contact anteally and 
ventrally. The stylet and stomachal attritor are present. 
This animal is a littoral species, inhabiting the shingle, and 
the sandy estuaries. It is also taken alive in the coralline zone. 
Bath, 21st January, 1851. 
I have stated above, that the foot has a byssal groove; a 
careful examination of a lively specimen sent me this day from 
Exmouth, proves that I was mistaken ; the foot, though rather 
smaller in proportion than im the next species but one, the 
Mya oblonga, nobis, the “ Lutraria”’ of authors, is, like it, 
without a trace of byssal groove; the branchiz and palpi of 
our present species, the type of the family, present the same 
