120 



cypeinidj:. 



Fig. 432. 



A. sulcata. 



centric furrows and ridges, the depressed portions wider than tlie 

 raised ones, vanishing at both ends, covered with a thick, greenish- 

 yellow or glossy, brownish-olive epidermis. 

 Hinge-margin strong, two teeth in the left 

 valve and one in the right ; interior pol- 

 ished, bluish-white ; muscular impressions 

 distinct. Length, one inch ; height, one and 

 one fourth inches ; breadth, three fifths of an 

 inch. 



Dredged alive near Governor's Island, in 

 four fathoms ( Stimpsoti) ; Marblehead Plar- 

 bor, at half-tide (Haskell); Halifax {Willis); Eastport, numerous 

 and many varieties (Cooper). It is the most common species 

 throughout all the Northern seas. Fossil in Labrador and about 

 tlie Gulf of ^St. Lawrence (Daiuson, Bell). 



Very small and half-grown shells are not uncommonly found in 

 the fish of Massachusetts Bay. It has been found by dredging in 

 Newport and Portland Harbors ; and occasionally a full-grown speci- 

 men is thrown up, with sea-weed attached, on our beaches. I have 

 no doubt it would l)e found in many places by dredging. Along the 

 coast of Maine it is common. At Augusta, Maine, Dr. C. T. Jack- 

 son found it plentifully in a partially fossilized state, and in com- 

 ])any with other shells, such as are now common on the coast of 

 Maine, imbedded in the earth many feet above high-water mark, 

 showing conclusively that that region has, by some cause, been 

 recently elevated above its former level. 



This shell seems to have caused much perplexity to all who have 

 undertaken to describe it. It is quite uncertain how many real 

 sj)ccies arc embraced in the above synonymes. The discrepancy of 

 authors, and the variety in the form and sculpture of the shells, 

 which must come under one or the other of the names, leaves us in 

 doubt. I have thought best to present them as one, and to include 

 them under the name which seems most a]^])ropriate of the three. 

 For, in the first place, the Venus Scotica and V. Danmonia of Mon- 

 tagu are clearly the immature and mature of the same shell; the 

 distinctive mark whicli he gives, viz. the smooth margin of the first, 

 and the cronulated one of the latter, being an insufiicicnt one. He 

 says: "The construction of the margin must be considered as invio- 

 lable ; no common shell whose character is to possess a plain margin 

 is ever found with a crenulated one, or vice versa.''^ Now, it is per- 

 fectly certain that no species of the genus is found with a crenulated 



