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



differ considerably among themselves as to the quality of water they 

 may select for their abode; Notonecta undulata, for instance, may 

 occur in the foulest kind of pools, while others must have compara- 

 tively clean water. 



The family Naucorid^e includes some broad, ovate forms which 

 seem to prefer waters well stocked with vegetable matter. They have 

 the usual talon-like fore legs, but as their hind legs are neither broad- 

 ened nor fringed with hair, they are poor swimmers, depending more 

 upon walking about upon the submerged plants. 



Of all of the Heteroptera perhaps the aquatic species have been 

 less well and accurately known to American entomologists than any 

 other group. This has been due to the fact that because of their 

 wide distribution, ease of collecting, and generally larger size they 

 received the attention of earlier systematists, who were satisfied to 

 give them but a brief and not distinctive characterization to make 

 them recognizable without an examination of the types. These types, 

 for the most part, having either been destroyed or deposited in mu- 

 seums abroad systematists have depended upon the meager descrip- 

 tions at hand, with the result that there has arisen considerable con- 

 fusion and uncertainty in fixing certain species. Especially is this so 

 in the family Corixidse. 



AQUATIC COLEOPTERA. 



By Chas. W. Leng, 

 West New Brighton, N. Y. 



Few, if any, beetles are aquatic throughout all the stages of their 

 existence; even those commonly called water beetles pupate on land 

 and sometimes at least lay their eggs on leaves out of the water. The 

 beetles which are more or less aquatic in habit include the several 

 families of water beetles, the Parnidse and Elmidse, the tribe Dona- 

 ciini in Chrysomelidae, some tribes of snout beetles and a few other 

 smaller families. All of these exhibit some modifications of struc- 

 ture and vestiture in harmony with their aquatic life, modifications 

 that are on the whole more marked in the adults than in the larvae, 

 especially in the case of the plant-infesting species; all exhibit a more 



