I7§ NEW YORK STATE MUSEUM 



rugosa and Macoma groenlandica, this species is 

 relatively rare. Only a few shells are anywhere near perfect, and the 

 larger shells are so broken that measurements can be only approximate 

 or not taken at all. The largest specimens must have had a length 

 of 45 mm to 52 mm and greatest width of 23 mm to 26 mm. The 

 rest of the specimens (not more than twenty-five collected in all, 

 besides the fragments) range from 31.8 mm x 19.5 mm to 43 mm x 

 23 mm, the majority running under 40 mm in length. The specimens 

 in general run from under one-half to about three-fifths the size 

 of the recent specimens, with the exception of the two or three 

 largest specimens. With the small number of specimens from this 

 locality, it is difficult to make comparisons; but the material seems 

 in general to run about the same as that from Port Kent and Lapham 

 Corners. 



M y a a r e n a r i a, like M y t i 1 u s e d u 1 i s, has been found 

 in only a few localities, but the Pleistocene specimens from the 

 Champlain area are so pronouncedly smaller and thinner than the 

 recent and Montreal Pleistocene specimens that they deserve 

 consideration here. Recent specimens from the New York coast 

 and Portland, Maine, range from 76 mm x 45.2 mm to 89 mm x 

 51.2 mm. Specimens from the shore of the bay at Ocean City 

 run considerably smaller, those used in comparison ranging from 

 64.2 mm x 39.5 mm to 69.6 mm x 42.2 mm. A large number of 

 fragments were found at Montreal, but no whole specimens. The 

 fragments show that the specimens were fully as heavy and must 

 have been comparable in size to the typical, adult recent specimens. 

 In " Geology of Canada " for 1863 (page 963) is figured a specimen 

 from the Montreal area measuring 85 mm x 50 mm, almost the size 

 of the largest recent specimen here used (see plate 3). 



Pleistocene specimens of this species were collected at Cumberland 

 Head (near Plattsburg); McBride bay, South Hero; and Valcour 

 island. The two largest specimens out of a collection of several 

 hundred specimens from Cumberland Head, measure 52 mm x 35 mm 

 and 50 mm x 31 mm. Other specimens range from 37 mm x 25 mm 

 to 44 mm x 30 mm. The majority of specimens have a length of 

 40 mm or less, though quite a number range between 40 mm and 

 44 mm in length. The South Hero specimens are smaller, if anything, 

 than those from Cumberland Head. The largest specimen in the 

 collection of several hundred from this area measures 52 mm x 33 mm. 

 Typical specimens range from 31.3 mm x 18 mm to 44 mm x 29 mm, 

 the larger number measuring less than 40 mm in length. This species 

 is much less abundant at Valcour island. Much of the material 

 collected is fragmentary and comparisons can be made on only 



