38 Journal New York Entomological Society. [Vol. xxi. 



matter are seldom found in clear water or that containing only sphag- 

 num moss. They must be sought in ponds rich in decaying vegetable 

 matter, and nothing was more marked in Labrador where such ponds 

 are non-existent than the scarcity of Hydrophilidse. Since they too 

 fly freely, for example the great Hydrous triangularis is often found 

 beneath electric lights, data drawn from occasional occurrence of 

 imagos must be used with caution. Notwithstanding this power of 

 flight and the consequent wide distribution of the species, the study 

 we made last winter of the local collection resulted in Mr. Winter- 

 steiner's discovery that the supposed Philhydrns cinctus of the sandy 

 regions of New Jersey was the more southern P. consors, affording 

 an instance of the restriction of a distribution of a species by climatic 

 conditions. As Mr. Sherman is to speak of the Dytiscidse and Mr. 

 Wintersteiner of the Hydrophilidse, I will continue myself with men- 

 tioning one more case of the distribution of water beetles being con- 

 trolled by environment. Hydrobius tesselatus is regarded by col- 

 lectors as exceedingly rare, but wherever a long dead log can be 

 found submerged in slowly moving fresh water, these beetles may 

 be found clinging to the under surface ; so Dr. Van Dyke and I found 

 it at Lakehurst, where a rough bridge had been made by throwing 

 logs down side by side across the stream, and Mr. Brownell has told 

 me of a similar experience at Westwood, N. J., where numbers of this 

 species were taken. 



In studying Elmidse we must resort to entirely new efforts in 

 collecting, for they are so securely attached by their powerful 

 claws to submerged stones, sticks and roots that ordinary methods 

 rarely show results. At Yaphank Mr. Davis, Mr. Engelhardt and 

 I waded into the shallow river and carried to the shore pieces of 

 board, branches, etc., that we found in the water, and allowed them 

 to dry out in the sun. On Staten Island and at Ramsey the same 

 plan has been tried, always with the same result, these long-legged 

 beetles commence to crawl away from the unwelcome light and heat 

 and are then easily detected. But in the water or out of it while 

 the stick is wet, they are liable to hide in crevices and defy detection. 

 There used to be a tradition that only swiftly flowing streams con- 

 tained such beetles, but Mr. Roberts long ago disproved it by finding 

 them in great numbers on the submerged roots of willow trees, grow- 

 ing close to river banks, so that the roots protruded from the soil into 



