152 SOLENIDAZ. 
SOLENID. 
Agreeably to our method, this family contams only two 
British genera, Solen and Solenicurtus ; the first has five, the 
latter, two species. Solen is a singular genus, its transverse 
measure in some species being 8 to 1 of the vertical. The 
foot occupies one end of the shell, the buccal orifice the middle, 
and the posterior portion contains the short siphons, which are 
nearly united, except in S. legumen, in which they are somewhat 
longer and more divergent. They have alliances with the | 
Gastrochenide, and by the long linear branchie with the 
Pholades ; but the ample notes on the principal species will 
give the necessary explanations. 
SOLEN, Linneus. 
S. stttqua, Linnzus et Auct. 
S. siliqua, Brit. Moll. i. p. 246, pl. 14. f.3; (animal) pl. I. f. 1. 
Animal subcylindrical, pale drab; the mantle is yellowish- 
white, tumid at the extremities, swelling beyond the margins 
of the shell, closed throughout, except a central narrow rayed 
slit, which appears to have no other use than to admit 
water to the branchiz, in aid of the pedal orifice, which in 
this family is greatly contracted by the shape and position of 
the foot ; it is also produced into a siphonal sheath, truncate 
at the extremity, bordered by a fine brown line, and which 
contains two short siphons, just separate at their termi- 
nations ; they are never extended much beyond the shell ; the 
upper is rather the shortest, and of less diameter than the 
branchial tube ; it is encircled by two rows of irregular cirrhi, 
which do not quite reach the orifice, the margin of which is 
plam; the lower one has about twelve rather long, tumid, 
pointed, white filaments; the upper, about twenty cirrhi, of 
three lengths and sizes, marked with fine brown lines and 
blotches at their bases, edges and summits; the branchial 
siphon has also two rows of similar cirrhi; in the lower one 
