84 SEVENTEENTH REPORT. 



Chaetogaster limnaei von Baer. Abuudant on Lyniimea stagnalis 

 apprcssa (Saj). 



Nais communis Piguet. Abundant in algae and on surfaces of 

 submerged vegetation. 



Stylaria, lacnstris L. Abundant in algae and on surfaces of sub- 

 merged vegetation. 



Pristina longiseta leid/yi Smith. Common in the vegetation of 

 beach pools. 



Aeolosoma tenehrarum Vejdovsky. Common in beach pools. 



The Discodrilidae are receiving attention from Dr. M. M. Ellis. 



CRUSTACEA. 



Cambarus diogenes Girard. This species is not included in the 

 list of Pearse (1910), as occurring in Cheboygan County, but is 

 abundant in a large beach pool at the east end of Douglas Lake and 

 was also found near the north end of Lancaster Lake. The late 

 summer ecdysis occurs about the middle of August and the males 

 then acquire the first form of abdominal appendages. 



MOLLUSC A. 



The onl}^ addition to the list of mollusks known to occur in the 

 legion is Lymnaea megasom<i (Say). Specimens were found in 

 abundance by the senior author and Dr. W. W. Cort in a pool at 

 the village of Indian River near the south end of Burt Lake in July, 

 1914. 



University of Illinois. 



