142 



MEMOIRS OF THE CARNEGIE MUSEUM. 



I obtained five specimens of this form in the black muck of Conneauttee Lake, 

 Edinboro, Erie Co. In the outlet of the lake (Conneauttee Creek) the creek- 

 form of ^4. grandis was more or less typically developed. 



Finally, it should be mentioned, that there are often specimens among typical 

 A. grandis, which are more swollen, thus approaching the var. footiana (to be dis- 

 cussed below). Such specimens sometimes are rather frequent at certain localities, 

 chiefly so in the uppermost Shenango River, at Linesville, Crawford Co., and 

 these forms are truly transitional toward var. footiana. It also should be empha- 

 sized that the form in Conneaut Creek, at West Springfield, Erie Co. (tributary to 

 Lake Erie) is the tj^pical creek-form of A. grandis. 



Anodonta grandis behaves in Pennsylvania exactly as elsewhere. Over the 

 wide range of this species we have a great tendency to form local races and eco- 

 logical forms, which in many cases have received names of their own, without 



Fig. 14. 



• Anodonta grandis. 

 ■ Anodonta grandis foolia?ia. 

 + Anodonta ohiensis. 



deserving them. I cannot go further into detail, since my material of the extra- 

 limital forms is not at all sufficient. But it is clearly seen that in Pennsylvania 

 as elsewhere this species is protean, accommodating itself to a variety of conditions, 

 and assuming different characters in shape and thickness of shell, in color, and in 

 size. It does not seem to reach in our state the extreme size recorded from other 

 parts (Baker, 1898a, p. 53, L. 171 mm.). However, one character generally 



