ARCACEA. MOLLUSCA. NUCULA. 99 



inch in height. He informs me that the animal is very active, and 

 that it leaps to an astonishing height, exceeding in this faculty the 

 scollop-shells. 



NUCULA MYALIS. 



Shell ovate, smooth, olive-colored ; anterior side longest and 

 rounded ; posteriorly acuminated, and sub-rostrated ; teeth about 

 twelve on each side. 



State Coll., No. 200. Soc. Cab., No. 2215. 



iNucula rayalis, COOTHOUY ; Bost. Journ. Nat. Hist., ii. 61, pi. 3, f. 7. 



Shell ovate, thin, slightly gaping at both extremities, moderate- 

 ly convex ; surface somewhat undulated by distant concentric 

 ridges, and covered with an olive-colored epidermis, arranged in 

 alternate darker and lighter zones ; beaks not elevated, a little 

 behind the middle ; anterior side semi-elliptical ; posterior side 

 sub-triangular, upper margin behind the beaks straight, compressed 

 and sharp to the very tip, which is obtusely pointed as the regular 

 curve of the base meets the dorsal line. Interior yellowish-white, 

 glossy, with greenish zones, and minute radiating lines or striae ; 

 cartilage cavity deep, triangular ; series of teeth about twelve on 

 each side, increasing in size and distance towards the outer ex- 

 tremities. Length ly 1 ^ inch, height T \ inch, breadth -f v inch. 



Taken from the stomachs of fish caught in various parts of 

 Massachusetts Bay. 



The general aspect of this species is like that of N. limdlula. It is 

 distinguished by the position of the beaks, and the smaller number of 

 teeth ; the whole shell, and the posterior side especially, is less elon- 

 gated, and the epidermis is of a darker, more strictly olive color, and 

 far less glossy. It never attains to so great a size. It has almost pre- 

 cisely the shape and size, but none of the oblique striae of N. drctica, 

 BROD. and SOWERBY. N. Aghtsii, COTJTHOUT, from the Antarctic 

 seas, must also be very closely allied. A shell from Spitzbergen sent 

 me by Dr. Loven, and named by him N. hyperlorea, as to the exterior 

 and the position of the beaks is like this ; but its height is less, and 

 there are eighteen teeth in the posterior range. 



