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



Mass., on pieces of old lumber in a small pond bordered on one side 

 by cat-tails and pickerel weed, with meadow land on the shore; and 

 on the other side full of sawdust and old lumber from an ice-house, 

 with a wooded swamp further back. 



Irrigation ditches are favorite places for collecting water beetles 

 in many regions where there are few other collecting grounds, and 

 under these conditions yield an abundance of species and specimens 

 especially if there is some motion to the water. 



II. Ponds and Pools of the Forest. 



In these the number of species is much smaller, but several of 

 them seldom occur anywhere else. 



My own favorite locality of this type at Peekskill, New York, 

 where Mr. Roberts and I have collected so successfully, may be 

 described as a swampy depression in the woods, a few hundred feet 

 above sea-level, filled with several small ponds more or less connected. 

 These ponds have for a bottom a deep bed of dead and thoroughly de- 

 composed leaves, but contain very little living vegetation except some 

 Sphagnum and in some spots a little grass. The woods are thick 

 enough so that the ponds are modefately well shaded. There used to 

 be a somewhat similar region in the woods adjoining the Moravian 

 Cemetery at Middletown, Staten Island, and there are similar but 

 smaller pools near the Great Falls of the Potomac on the Virginia 

 side. 



In all three places practically the same species occur as follows : 

 Bidessiis fuscatiis Crotch, Ccelambus laccophilinus Lee, Hydroporus 

 tristis Payk., Hydroporus difformis Lee, Ilybius ignarus Lee, Matus 

 bicarinatus Say, Agabetes acudnctus Harr., Agabus scmipunctatus 

 Kby., Rhantus sinuatus Lee. 



The shaded ponds in Forest Park, Long Island, formerly furnished 

 some of these species, but lately these ponds have become contami- 

 nated and most of the vegetation has been destroyed, so that this 

 fauna has largely disappeared. 



While the living vegetation of these forest ponds is not extensive, 

 the little there is, seems to be essential. At Peekskill last year we 

 found that the vegetation had been mostly killed perhaps by the 

 drought of 1911, and water beetles were extremely scarce. At Peek- 

 skill too, the forest is gradually disappearing, and with it, no doubt, 

 these Dytiscidae also. 



