REPORT OF THE DIRECTOR 1920-21 171 



are based. The specimens of Macoma groenlandica 

 collected at Montreal numbered about 225; at Ottawa and vicinity, 

 about 50; at McBride Bay, South Hero, 150; at Cumberland Head, 

 over 300; at Valcour island, over 160; at Lapham Corners, 115; 

 at Port Kent, over 1000; at Burlington and vicinity, over 200; at 

 Willsboro, several hundred; at Essex, over 150; at Port Henry 

 vicinity, over 250; at Chimney Point, about 150; at Crown Point, 

 over 150. The specimens of Yoldia arctica collected at 

 Ottawa and vicinity numbered over 450 (about 375 at Ottawa); 

 at Burlington and vicinity, about 7 5 (largely fragmentary) ; at 

 Port Kent, over 350; at Willsboro, about 20; at Chimney Point 

 12 (fragmentary). The specimens of Saxicava rugosa, 

 collected at Montreal numbered no; at Ottawa and vicinity (almost 

 entirely Green creek), about 275; at South Hero, 3 (small); at Bur- 

 lington and vicinity, 7 (fragmentary); at Port Kent, about 300; 

 at Willsboro, about 300. The specimens ofMytilus edulis 

 collected at Lapham Corners numbered several hundreds; at Port 

 Kent, 20+ (fragmentary) ; at Willsboro, 25+ (fragmentary); at 

 Port Henry, few small fragments. Specimens ofMya arenaria 

 were collected to the number of several hundreds at McBride bay, 

 South Hero, and at Cumberland Head; at Valcour island, about 

 25+ specimens (largely fragmentary). 



Macoma groenlandica is the only species found 

 extending the entire length of Lake Champlain, the most southern 

 occurrence, as noted above, being 2 miles south of Crown Point 

 station. Professor Cook, in reporting the two new occurrences 

 for this species stated that, so far as he could recall, the shells in 

 size and character resembled those from Crown Point. The writer 

 has not, as yet, had any opportunity for studying the shells collected 

 in the vicinity of Crown Point station ; and therefore it is the speci- 

 mens from the Crown Point area, about 8 miles farther north, that 

 are used here for purposes of comparison. The recent shells used 

 in comparison are from the New Jersey and New York coasts. The 

 largest recent shell examined has a length of 33.4 mm and a width 

 of 25.5 mm. The other shells vary from 25 mm to 3 1.3 mm in length 

 by 19 mm to 26 mm in width. The largest shells found at Montreal 

 were in a fragmentary condition, but in proportion to the measure- 

 ments of the other shells must have reached a length of 24 mm to 25 

 mm with a width of 20 mm to 21.5 mm. These very large shells were 

 found to be fewer in number; a large proportion measure from 19 

 mm to 2 2 . 5 mm in length by 1 6 mm to 2 o mm in width . The ma j ority 

 of the shells found, or what might be termed the average shells, are 



