REPORT OF THE DIRECTOR 1920-21 1 77 



sufficient for making comparisons. In the Canadian area, in addition 

 to the Montreal material, specimens were collected at Ottawa and 

 vicinity. At Ottawa only a few small specimens were found, 

 decidedly not typical; but at Green's creek, along the Ottawa river, 

 8 miles below Ottawa, more typical material was found, though 

 not in great abundance. The shells found range from average-sized 

 specimens with a length of 15 mm and width of 7 mm to the largest- 

 sized specimen with a length of 25 mm and width of 13.8 mm, giving 

 measurements well under those for Montreal. 



Mytilus edulis was found only in small numbers south of 

 Lapham Corners; and this is the most northern locality in the 

 Champlain area from which the writer has shells for comparison. 

 Specimens collected here number up to several hundreds. The 

 largest specimens range from 38 mm x 20 mm to 45 mm x 20 mm 

 and 43 mm x 25 mm. Sizes varying from 33 mm x 17 mm to 

 41 mm x 18 mm are abundant, but a large part are smaller. The 

 larger specimens in the case of this species are used for comparison, 

 because I have only the larger, representative recent forms and in 

 some localities only enough specimens have been found to make 

 such a comparison. Recent forms from the New York coast range 

 from 68 mm x 32.1 mm to 77.5 mm x 35.2 mm; from Cape May, 

 68 mm x 29.7 mm to 76.4 mm x 35.3 mm. Specimens from Gay 

 Head, of " average adult size for the locality and station " run 

 somewhat smaller than those from the two preceding localities. 

 The largest specimen at hand measures 68.3 mm x 30.7 mm. The 

 larger Lapham Comers specimens run one-half to three-fifths and 

 less the size of the largest recent specimens. No specimens have 

 been obtained from the Montreal area. A specimen figured in 

 " Geology of Canada " for 1863 (page 963) measures 40 mm x 

 20.5 mm, but I should regard this as small for the area. {See plate 2, 

 figures 1-3.) 



Farther south, at Port Kent, only about a dozen specimens at all 

 complete were found. The largest specimens measure 52 (?) mm x 

 27 mm and 46 mm x 22 mm; the rest of the specimens range from 

 32.5 mm x 18.5 mm to 43.7 mm x 27 mm. The largest specimens 

 run about three-fifths the size of the largest recent specimens; most 

 of the other specimens run one-half, and less, that size. At Willsboro, 

 a short distance farther south, the shells are heavier than at Port 

 Kent and, particularly, Lapham Corners. I think this is due to 

 the fact that the limy layer has been dissolved away to a large 

 extent in the specimens from the last-named places. As noted 

 above, at Port Henry only small fragments were found, and these 

 of rare occurrence. At Willsboro, compared with Saxicava 



