ZOOLOGY. 
ccxli 
long and slender, and the whorls more convex ; the aperture ovate instead 
of roundish-ovate. The specimen brought home appears to be young . 
Class. — CONCHOPHORA. 
Order. — Pachypoda. 
Fam. — Myade^. 
Genus. — Mya. Lin. 
Species. — Mi/a truncata. List. Conch, t. 428, f. 269. 
Order. — Leptopoda. 
Fam . — Nuculid.® . 
Genus. — Nucula, Lamarck. 
'** Shell behind slightly produced, gaping ; edge entire. 
Species. — N. arctica. 
Testa ovali-elliptica, laevis, tenuis, fragilis, flavescens ; latere antico lato, 
rotundato, postico brevi, oblique truncato. 
Nucula arctica, Gray ut supra. 
Shell oval-elliptical, smooth, very slightly concentrically wrinkled; epidermis 
yellowish-green, glossy ; umbones rather acute, nearly central ; broad 
rounded, rather narrowed, obliquely truncated behind ; inside glossy-white, 
edge plain in front ; length (from front to back) half an inch ; depth (from 
umbones to the opposite edge) a quarter; breadth (from the outside of one 
valve to the outside of the other, in the most convex part) one-sixth. 
*** Shell behind much produced, gaping, above depressed. 
Species. — N.rostrata, Lamarck Hist., vi., 58. 
Area minuta, O. Fabr., Faun. Groenl., young ? 
Area rostrata, CAem. Conch., vij. 106. t.55. f. 550. 551. — not, Mont; 
Shell, length 7-8ths, depth 3-8ths, breadth 2-8ths, of an inch. 
Animal, Mantle-lobes, separate from one another ; foot compressed, sub- 
quadrate, front rent; gills attached to the hinder part of the mantle, as in 
the Pholades and Myae, , 
Order. — Phyllopoda. 
F am. — Hyatellad^. 
