156 The Ohio Journal of Science [Vol. XXI, No. 5, 



were of this species. (A number of very young ones were too 

 small and undeveloped for determination). The only male 

 crayfish found was a half grown one of this species, from the 

 mud of station 11. The others were females, two small ones 

 and one quite large, all in soft shelled condition. All were from 

 the small pond. 



Cambarus bartoni robustus (Girard). Only one specimen 

 of this species was found, a female of medium large size, taken 

 at station 13. As this is a common "brook species," found 

 among stones in rapidly flowing streams, (Pearse, '09) its 

 presence in Mirror Lake was somewhat surprising, though it 

 should be noted that having been found among stones near the 

 north shore of the large pond, it was not as far from its habitat 

 as it would have been in the small pond. 



Class Insecta. 



The aquatic members of this class living in Mirror Lake 

 were so numerous in kinds and individuals that they actually 

 formed the dominant assemblage of animal inhabitants of the 

 small pond, though they were reduced to a place of minor 

 importance by the fishes in the large pond. Most orders, 

 including aquatic forms, were represented here. 



Order Collembola. 



Springtails apparently were not abundant on the pond as a 

 whole, but when found at some restricted area, as happened 

 a few times, they were abundant in those places. 



Sminthurides aquaticus (Bourlet) was a rare species; only 

 one specimen was so identified out of all Collembola obtained. 



Isotoma palustris (Miiller) was a species of undoubtedly 

 uncommon occurrence also; only three specimens were secured. 



Podura aquatica Linn., was the most numerous by far of 

 the Collembola here. It was abundant a number of occasions at 

 some areas, and with better collecting methods decidedly more 

 would have been obtained than the table shows. Possibly 

 smaller and hence less conspicuous numbers were present in 

 other parts of the pond also. 



Order Ephemerida. 



Larval stages only were taken, of the mayflies. No adults 

 were noticed, not even a trace of their bodies after their ephem- 



