THE NAUTILUS. 59 



38. Physa ancillaria Say, tf 1879 to 1885. 



39. Aplexa hypnoram Linne, tt 1883. 



40 Valvata tricarinata Say,* found in driftwood at the tail race 

 of the " Big Run," spring of 1881. 



41. Campeloma decisum Say, | O'wasco River near Owaseo Lake, 

 August, 1882, also in Owaseo River three miles below lake. 



AGASSIZ ASSOCIATION DEPARTMENT. 



[Conducted in the interest ol the Isaac Lea Concholngical Chapter <>f the 

 Agassiz Association, by its Genera] Secretary, Dr. W. s. .strode.] 



During the last year I have done all the work possible towards 

 collecting the Pisidia of the northeast of Maine. About 50,000 



specimens have been obtained and worked over by Dr. V. Sterki of 

 New Philadelphia, Ohio. The material has been finely preserved in 

 nearly every locality. The cold water of our streams is favorable 

 for the development of this minute clam. In all about twenty 

 species and some varieties have been obtained. Many of these 

 species have proved new to the State, and a few have been published 

 by Dr. Sterki as new species. A part are very difficult to identify 

 until a larger amount of material is obtained. It sometimes results 

 that among thousands of specimens there will be only one individual 

 representing a certain species. Pisidium contorlum Prime, has 

 been found living in a small lake in the northeast of Perham. It 

 had heretofore only been found fossil, in Maine and Massachusetts. 



The little Pisidiiun milium Held, so common in the north of 

 Europe (a straggler like myself), has been found living in the south 

 branch of Caribou stream in Woodland. It is curious how this liitle 

 creature came across the ocean. 



Two years ago I found Planorbis crista Lin., var. cristata Drap., a 

 species of Northern Europe, in Barren Brook, Caribou. This sum- 

 mer I have found it fossil in the marl deposit of Lovely Brook in the 

 town of Fort Fairfield. I think this is proof that it was not imported 

 by any accident or in the outfit of any emigrant coming to this con- 

 tinent. In my last report I had about 81 species collected in this 

 region. This year I have of land shells 33 species, fresh water gas- 

 tropoda 23 species, and of Unio 1, Margaritana 2, and Anodonta 1 

 species; Sphserium 5, and Pisidium 20 species and several varieties. 



