182 NEW- YORK FAUNA MOLLUSCA. 



Mytilus BOREALIS. 



plate xiii. fig. 222. 



(STATE COLLECTION.) 



Mytilus borealis. Lam. An. sans vert. Vol. 3, p. 21, No. 25, Ed. Brux. 

 M. edulis, GocLD, Invertebrata of Mass. p. 121, fig. 82. 



Description. Shell solid, elongate, subtriangular, somewhat ventricose, smooth, shining, 

 flattish on the posterior and somewhat angulated and keeled on the anterior margin. Beaks 

 tumid, pointed. Hinge an inch long, with numerous tooth-like elevations and cavities. Basal 

 margin curved and scooped out, with a small fissure for the passage of the byssus. 



Color. Black or greenish black ; within blue-black on the margin ; purplish and bluish 

 white in the cavity. 



Length, one to two and a half inches. 



This species is common on the northern seacoast of the United States. On the coast of 

 Long island it is used to some extent, as well as the M. plicatula, as a manure, for which 

 eighteen cents per bushel is paid. 



We follow Lamarck in considering this as distinct from the common edulis of Europe, with 

 which, however, it is closely allied. In several specimens, it may admit of doubt whether 

 the beaks are even terminal. There is a variety. 



Mytilus notatus. 



PLATE Xm. FIG. 223. 



(STATE COLLECTION.) 



Description. Shell oblong, oblique, with minute concentric strias, smooth, compressed, 

 angulated on the anterior side, regularly rounded on the basal margin, which is entire ; the 

 posterior margin slightly plicate. Beaks distinct, contiguous, terminal : a small bifid tooth 

 under the beak, received into a corresponding depression in the other valve. 



Color. Reddish brown, with deep purple zigzag marks ; posterior surface chesnut-brown ; 

 within bluish purple, iridescent. 



Length, 1-7. Width, O'S. 



I am not sure whether the following species, which is regarded by some conchologists as a 

 variety of borealis, may not be identical with notatus. 



