March, 1913] ShERMAN : HaBITS OF THE DyTISCID^. 45 



attracted by the rain water resting in the axilla of the leaves, and 

 that others originated in the water with which the leaves were 

 washed. The Dytiscidcc were chiefly of the genera Canthydrus, 

 Bidessus, Laccophilus, Desmopachria, Notoniicrus, Hydrovatiis, 

 Cclina, and Hydrocanthus, as the tobacco came from southern coun- 

 tries. Two North American species (from Mexican tobacco) were 

 mentioned — Bidessus affinis Say and Bidesstis piilliis Lee. 



The Dytiscidae are also often washed up on the ocean beaches and 

 on the shores of the Great Lakes, by tide or wind, though none of the 

 species live either in the ocean or in the open waters of the big Lakes. 



Few species live in salt or brackish water. A few are often 

 found in it, though most of such species occur also in water which is 

 not salt or brackish. Ca^lambus inipressopunctatus Sch. is taken on 

 the salt marshes of Staten Island, but this is a widely distributed 

 species in the north, occurring both at the sea level and at high alti- 

 tudes, both east and west. Mr. Loding, of Mobile, Ala., mentions 

 Coptotomus, Laccophilus proximus Say and fasciatus Say, and Ther- 

 monectes hasilaris Harr. as occurring in brackish water, and says the 

 latter also lives in quite saltish water. The lately rediscovered 

 Agahus lineelus Lee. lives in the salt marshes near San Francisco, 

 Cal. 



In an inlet of the Hudson River just below Peekskill, New York, 

 where the river water is still salt, under stones, sticks, dead leaves or 

 other debris on the mud at or below the high tide mark, Copclatus 

 glyphicus Say used to be very common. This species is associated by 

 Mr. Leng with cat-tails and he points out that with its thin flat body, 

 it is well adapted to live among the cat-tail sheaves. The place near 

 Peekskill was covered with an extensive growth of cat-tails. I believe 

 Mr. Bischoff of Newark finds a number of species of Dytiscidae in the 

 cat-tail sheaves early in the spring, which have hibernated in this 

 shelter. 



Celina angustata Aube occurs in some ponds on Staten Island 

 where there is some iron in the water, and Mr. Shelford found some 

 species in similar ponds near Chicago, 111., but usually if the per- 

 centage of iron is great there are no beetles, c. g., the pools along the 

 eastern branch of the Potomac at Bladensburg, Md. 



Dytiscidae live both in very cold and in very warm water. Mr. 

 Schwarz has taken Deroncctcs striatcllus Lee. in water having a 



