March, 1913.] ShERMAN : HaBITS OF THE DytISCID^. 47 



hybridus Aube, Thermonectes basilaris Harr., Graphodercs cinereus 

 Linn., Colymbetes scidptilis Harr. ,and Rhantus notatus Fabr. 



Almost the same species occur in similar meadow ponds in the 

 vicinity of New York City. Ccclambus acaroidcs Lee. and Rhantus 

 notatus Fabr., however, are western species exclusively. The genus 

 Rhantus is commonly represented here by binotatus Harr. Two 

 genera not mentioned by Needham contribute two common species to 

 the meadow pond fauna, Hydrocanthus iricolor Say and Desniopachria 

 convexa Aube. 



Needham calls attention to the general correspondence in the 

 size of the various species with the depth of water in which they 

 are found, Dytiscus being usually found in the deep water — two or 

 three feet,- — with Aciliiis adjacent on the shoreward side, and Copto- 

 tomtis " in water a foot deep in the narrow aisles between the typha 

 clumps. Laccophilus dwells amid the fallen stems and trashy accu- 

 mulations nearer shore, Hydroporus and Ccr Iambus love the shoals 

 into which one can look down while sitting on the bank, while Bides- 

 sus clings to the very shore line." 



The Lake Forest pond is considerably larger than the ponds in 

 which I have been most successfuL Nor does the limitation of vege- 

 tation to the typha type sound especially attractive. 



A collection of smaller ponds somewhat connected, and located in 

 wilder country, like the ponds at the edges of the woods near the 

 railroad trestle of the C. R. R. of N. J. crossing the brook a mile and 

 a half north of Lakehurst, N. J.— ponds first explored by Mr. Leng 

 and now familiar to us all — such a group of ponds provides an ideal 

 home for the Dytiscidse. About 40 species live in these Lakehurst 

 ponds. Ccclanibus farctns Lee. replaces acaroidcs Lee. of the Lake 

 Forest list while Rhantus is represented by calidus Febr. — a more 

 southern species. 



In Agabus we have at Lakehurst tccniolatus Harr. and ccriiginosus 

 Aube. The presence of this genus suggests in each case the spring- 

 fed nature of the ponds. In Bidcssus there are pulicarius Aube, which 

 becomes commoner as we go further south, and also fuscatus Crotch, 

 the latter being usually a forest species in the north. The genus 

 Canthydrus is also represented at Lakehurst. 



Canthydrus puncticollis Crotch, which has been considered a rare 

 beetle, was found last May by Mr. Norman S. Easton at Fall River, 



