NATURE STUDY IN SCHOOLS. 189 



NOTES ON SOME FRESH WATER CLAMS. 



BY 



Austin Clark. 



(Read before the Mavnard Chapter of the Newton Natural History Society, 



Sep. 15, 1899.) 



There is no branch of Natural History more fascinating, perhaps, than 

 the study of shells, and among the shells, some of the most interesting groups 

 to study are those inhabiting our ponds and rivers. I refer especially to those 

 called fresh water clams or mussels. 



Although in our vicinity we have few very striking species, still even 

 our smaller ones are sufficiently beautiful to justify a close study of them. 



We have, or used to have, right here in Newton a very large local race 

 of a shell called Unio nasutus, or long-nosed clam, from its having its siphon 

 end very much lengthened. The specimens I have came from Lake Cochi- 

 chuate in Natick, and are of ordinary size. The specimens which used to 

 occur in Bullough's Pond in Newtonville before it was drained, were almost, 

 if not quite, twice as long as these, and of a .beautiful pink inside. 



Another of our clams is the Alasmodon arcuata, a long, narrow shell, 

 occurring sometimes five inches in length. It lives in running streams, wherever 

 the pearl-hunters have not exterminated it. 



With the exception of these two clams, our New England mussels are 

 of no interest to those who do not make a specialty of them. But if we go 

 westward, into the Mississippi basin, we find clams which at once attract at- 

 tention from their size, shape, or peculiar coloration. We have good reason 

 to be proud of our shells when we remember that, of all the species of fresh 

 water clams discovered, more than half are native of the United States. 



One of the most striking of our clams is the Unio alatus, or winged 

 clam. It occurs, generally sparingly, in most of our western rivers, and also 

 in Lake Erie and Lake Champlain. It prefers a muddy bottom, and is gen- 

 erally found buried to the base of the hinge or " wing." Sometimes it occurs 

 on gravel, or on rocks, lying on the surface. When in the mud it clings so 

 well with its foot as to be difficult to pull out. In size it is one of the 

 largest of mussels, sometimes being found six inches long, by four wide. I 

 can recall at this moment but one larger clam, and this occurs in the Amccr 

 region of China. 



Another large clam, weighing far more than the last, is Unio plicatus, 

 with its varieties, Unio undulatus and Unio multiplicatus. Although not 



