1 82 NEW YORK STATE MUSEUM 



larger than the Pleistocene specimens. An average size for specimens 

 of Trivia trivittataoff the Massachusetts coast is two-thirds 

 of an inch long by one-third of .an inch greatest diameter; an average- 

 sized fossil specimen is three-eighths of an inch long by a greatest 

 diameter of three sixteenth of an inch. An average specimen of 

 Mulinia lateralis from the New England coast has a length 

 of nine-tenths of an inch and a width of six- tenths of an inch. One 

 of the larger of the fossil specimens measured five-sixteenths of an 

 inch by one-fourth of an inch. Shimer further points out: " The 

 young shells off the coast are small, thin, with margins subequally 

 rounded and beaks inconspicuous and nearly touching each other; 

 this description applies to all of the Hudson River specimens. It 

 does not seem probable, however, though possible, that so many 

 shells could be gathered at random as was done by the drill without 

 getting some adults. The more probable explanations seems to be 

 that these fossil individuals were living in an unfavorable environ- 

 ment, a water less than normally saline, and through a constant 

 sapping of vitality, were not able to attain large size " (p. 489). 

 Recently a few specimens of Mulinia lateralis were collected 

 at Croton Point about 20 miles south of Storm King. The largest 

 one measured 11.9 mm x 8.5 mm (i. e. about seven and one-half 

 sixteenths of an inch long); a smaller specimen measured 7.1 mm x 

 5.3 mm (i. e. about four and one-half sixteenths of an inch long). 

 The larger specimens from Storm King run somewhat smaller than 

 the largest specimen from Croton Point, as one might expect in 

 waters of decreasing salinity; but the latter is still only about one- 

 half the size of average recent forms, under normal conditions. 

 In the sandy layers at Croton Point, a few feet above the water's 

 edge, occurs a bed of oysters (Ostrea virginiana Lister) , 

 similar to the thick S a x i c a v a beds found in some localities in 

 the Champlain area and Canada. In one place the bed reaches 

 a thickness of about 30 inches, but it quickly thins out and varies 

 from 12 and 14 inches to about 6 inches; following around the point 

 to the shore on the north side only a thin line of shells is found. 

 It has been popularly assumed that this bed of oysters represents 

 an Indian shell heap. Prof. A. W. Grabau, I understand, some 

 years ago, in a paper which I have not been able to locate, describes 

 this occurrence of oyster shells as an oyster bed rather than a shell 

 heap 1 ; and the evidence which I have collected seems to indicate the 



1 Woodworth (p. 187) after an examination of this oyster bed concluded that 

 the shells were in a talus and derived from an old shell heap at the top of the 

 bluff. 



