March, I9I3-] LenG : AqUATIC COLEOPTERA. 41 



Donacia. A considerable number of snout beetles besides those 

 already mentioned attack aquatic plants and should be included. 

 Listronotus latiuscidns was found by Dr. C. M. Weed in all its stages 

 in the stems of Sagittaria variabilis; L. appcndtculatus by Mr. W. 

 Jiilich, in the stems of reeds; Macrops solutus and sparsus also breed 

 in the stalks of Sagittaria. Some species of Lixus have been bred 

 from stems of Polygonum amphibiitm by Popenoe, Lissorhoptnis lives 

 on the roots of rice, and the various species of Sphcnophonis also 

 infest the roots or lower parts of the stems of graminaceous plants, 

 including those that grow in wet places. These Rhynchophora are 

 here included because their surface indicates an adaptation to aquatic 

 conditions, being clothed in every instance with hydrofuge pubescence 

 or with imbricated scales. These are but a few instances of beetles 

 dependent upon plants growing in water. Many others could doubt- 

 less be cited by those collectors who have specially studied ponds 

 and swamps, and much remains to be learned in regard to the food 

 plants of our local palustral Coleoptera. 



Special Questions. 

 As to salt or brackish water, I think it may be said that at best it is 

 tolerated by beetles. Philhydrns hamiltoni seems to be a denizen of 

 salt marshes exclusively, but all the genera and most of the species 

 of Hydrophilidas found there would also be found elsewhere and in 

 greater numbers. In other families I know of no salt water species. 

 The difference between stagnant and moving water is on the contrary 

 very marked in its influence. The Parnidse and Elmidae, which are 

 comparatively stationary, must depend upon the current bringing them 

 air, hence practically none are found in still water. Most of the Hydro- 

 philidse feed upon decaying vegetation, and would be ruined where a 

 swift current kept the bottom clean, hence the members of this family 

 are seldom found in moving water; but there are all degrees of motion, 

 and between a stagnant ditch and a slowly moving swamp the differ- 

 ence in respect of motion is not great, and leads up so gradually to 

 the slowly moving streams of flat plains that one is not surprised to 

 find Parnidse and Elmid?e in sphagnum bogs or Hydrobius beneath 

 submerged bridge logs. As I have before pointed out a moderate 

 degree of flexibility in habits will tend to broaden the distribution of 

 a species, while the converse would go far towards entering it in the 



