March, 1913.] LeNG : AqUATIC CoLEOPTERA. 39 



the water. Dr. Lutz has also taken them in numbers by roughly 

 brushing the banks and bottoms of brooks, catching the loosened 

 mud and insects in a piece of cheesecloth stretched across the brook 

 lower down. It is evident that what the Elmidje require is aerated 

 water, and their formerly supposed dependence upon swiftly flowing 

 streams only results from such being always well supplied with air. 

 The occurrence of Psepheniis Iccontci at Niagara and other waterfalls 

 is simply an extreme instance of this necessity for aerated water. 



The difficulty attached to collecting the Elmidse and perhaps the 

 scarcity of suitable waters near New York have prevented us from 

 doing a great deal with them, even the taxonomy is in a very unsettled 

 condition ; some of our local species including possibly one of those 

 found in the Carman River at Yaphank, being still unnamed. The 

 occurrence of some species will undoubtedly be found to depend 

 upon the existence of certain conditions required for their welfare, 

 and it is evident that we have in Macronychus glahratus a species that 

 can accommodate itself to the slower moving streams, and is there- 

 fore relatively common at least on Staten Island, but we know too 

 little about the other species to venture any comment at present.^ 



Of the other smaller groups of beetles aquatic in some stage, we 

 know still less. We have no Georyssid3e in this vicinity, nor any 

 Hydroscaphidae. The Dascyllidae are said to have aquatic larvae, but 

 no local collector has ever followed the matter up. 



COLEOPTERA OF AqUATIC PlANTS. 



In the preceding paragraphs we have been principally occupied 

 with insects that frequent aquatic environments primarily for the sake 

 of the water and what it contains, and we have noted in how many 

 respects, in locomotion, in respiration, in vestiture and form they are 

 modified to fit them for aquatic existence. Further, we have been 

 able to discern how for each a special environment suited to its in- 

 dividual needs, is more or less essential to its existence. But in no 

 instance has this environment so far involved special relations with 

 a particular species of the plant world. There are, however, very 

 many beetles living upon aquatic plants, modified to fit them for 



^ A curious statement in reference to Elmidse is found in E. A. Butler's 

 " Pond Life " to the effect that they occur in great numbers in the Cordilleras 

 and are worked up with dough into lumps and sold under the name of 

 " Chiche," the dish prepared from them being called " Chupe de chiche." 



