426 Annals of the Carnegie Museum. 



are recognizable, though rather small. A number are more or less 

 deformed and crippled, though probably the same ; a few are markedly 

 different, and are apparently 6". truncatiim Linsley. 



4. Sent with the preceding from the vicinity of Lake Cushman, 

 Mason County, Washington, collected by i\Irs. Helen T. Gaige, are 

 some Sphccriidcv of particular interest. I shall first mention Sphccriiini 

 patella Gould from several localities. The original description of 

 this species, as cited by Prime in Alon. Corb., p. 42, is evidently based 

 upon quite immature specimens: long. 10.75; lat. (=alt.) 7.75; diam. 

 4.5 mm. Those before me range from smaller sizes, than those just 

 given, to specimens 15 to 16 mm. long, and still larger individuals have 

 been seen before from other places. Pisidium variahile Prime, appar- 

 ently like eastern forms, and markedly different from the form 

 magnum from other places in Washington. For P. notoplithabni n. 

 sp., (see infra, Description No. 8). P. columhianum Sterki was sent, 

 an exceptionally small form and otherwise somewhat different, hav- 

 ing the beaks markedly flattened on top. 



Included in a sending received from Dr. Bryant Walker was a lot 

 of shells from the beach-drift of Saginaw Bay, Lake Huron, collected 

 by Mr. Calvin Goodrich, including several forms of Sphcrrium spp., 

 which furnish valuable aid in studying the Sphccria of the Great 

 Lakes. Among them are several peculiar forms, which can not be 

 identified with those now known. Alore good material from all of 

 the Great Lakes, especially material taken by dredging, is very de- 

 sirable. In the lot were numerous specimens, mostly young and im- 

 mature, identified as P. a;;n;/r;/;H ( iorm sfriolatum Baudon ?) from Lake 

 Ontario, supposed to have been introduced from Europe. One young 

 shell of the same form has also been seen from beach-drift at the 

 southern end of Lake Michigan. This may reopen the question 

 whether the species is indigenous in North America. So far as is 

 known it has not been found fossil on this continent. If the mussels 

 were colonized in Lake Ontario, they may w^ell have spread to the 

 upper lakes. It may be added that repeated careful comparison has 

 shown that the mussel from Lake Ontario is identical with specimens 

 from England, France, and Germany, while other forms of amnicum 

 are rather different. 



