ORTMANN: monograph op the naiades of PENNSYLVANIA. 171 



0.33 X 0.33, while my measurements for the typical form (1912, p. 294) are: 0.32 

 X 0.32 mm. 



Breeding season: Not observed. According to Surber gravid specimens have 

 been found in September and October. 



Remarks: The subcylindrical, more elongated shape of the shell is the only 

 reliable character by which this form may be recognized; and even this is not 

 always equally well-developed. Lake Erie specimens may incline toward the nor- 

 mal form, and, on the other hand, more swollen individuals may turn up in the 

 Ohio-drainage, chiefly in the lake environment. 



Special attention should be directed to the fact that in Conneaut Creek, 

 tributary to Lake Erie, the typical form is found; and parallel to this is the fact 

 that likewise from tributaries of the lake in northwestern Ohio and southeastern 

 Michigan this form is at hand. 



In Lake Erie, principally in the beach-pools and ponds of Presque Isle, the 

 var. buchanensis is also characterized by its color. The latter is not greenish; 

 but is reddish brown, generally beautifully reddish chestnut near the beaks, shading 

 to dull dark brown and blackish upon the disk and toward the margins. In most 

 cases rays are very obscure or entirely absent, with the exception of a few indistinct 

 blackish ones upon the posterior slope. This color, however, certainly is only a 

 local, environmental effect. It resembles much the color observed in the beach- 

 pool form of Anodorita grandis footiana, but is more intense, and, moreover, not 

 all specimens from Presque Isle have it. From the bay I have specimens, which 

 are distinctly green, with distinct rays, and hardly any rusty brown. Such speci- 

 mens agree very closely with specimens from Conneaut Lake, and the connection 

 of the variety with the type is thus complete. 



Localities represented in the Carnegie Museum: 



Lake Erie, Presque Isle Bay, and beach pools of Presque Isle, Erie, Erie Co., Pennsylvania. 

 Pond at mouth of Elk Creek, Miles Grove (North Girard), Erie Co., Pennsylvania. 

 Lake Erie, Port Dover, Norfolk Co., Ontario, Canada (C. Goodrich). 

 Lake Erie, Buffalo, Erie Co., New York (Hartman collection). 

 Raisin River, Adrian, Lenawee Co., Michigan (C. Goodrich). 

 Lake Huron, Port Huron, St. Clair Co., Michigan (N. M. Gricr). 

 Bessey Creek, Cheboygan Co., Micliigan (H. B. Baker). 

 Scioto River, Kenton, Hardin Co., Ohio (C. Goodrich). 



Distribution and Ecology (See fig. 16) : Type locality, Buck Creek, Ohio (Lea).'-^ 



In Pennsylvania this form is restricted to I.,ake Erie, and is found there in 



great numbers, chiefly in certain beach-pools on Presque Isle. It lives there in 



'-^ Location unknown. Possibly near Cincinnati? 



