98 



Gyrinus, larva. 



A small larra about .25 inch long, from Wood Slough, agrees 

 exactly with published accounts of larvse of this genus. Only one 

 example was taken, though doubtless they were common, judging 

 by the abundance of adult beetles. 



Family Hydrx)PHILId.e. 



The beetles of this family bear a close general resemblance to 

 the predaceous water beetles, from which they may be known by 

 their clubbed antennae. The legs, though generally somewhat 

 flattened, are moved alternately in swimming, and are not as ef- 

 ficient for rapid locomotion as are those of the Dytiscidse and 

 Gyrinidee. In the beetle state the food is largely decomposing 

 vegetable matter. Occasionally the large species attack mollusks 

 or amphibians. The larvee are carnivorous, and, like those of the 

 Dytiscidse, do a good deal of damage in fish ponds. They have a 

 single tarsal claw. The labrum is wanting. The 8th pair of 

 spiracles is terminal, and the posterior end of the body is devoid of 

 hooks. Some have fringed appendages along the abdomen like 

 those of Gyrinus larvse. The eggs are placed by the female in a 

 silken case, sometimes attached to leaves or sticks which keep it 

 at the surface, in other cases carried about by the beetle. A sin- 

 gle case may enclose a hundred or more eggs. After hatching, 

 the young larvse remain for some time in the case, where they are 

 protected from their enemies and insured a supply of air by be- 

 ing kept at the surface. A European species, very similar to our 

 large black Hydrophilus, becomes fully grown as a larva in one 

 hundred days, and leaves the water to burrow in the earth for 

 pupation. The beetles hibernate in the mnd and under rubbish 



Hygrochus squamier, Lee. 



(LeConte., Proc. Acad. Nat. Sci. Phil., vii, 359, 1855.) 

 Found in Willow Slough August 15. Not common. 



Hydrophilus ninibaius, Say. 



(Say, Jour. Acad. Nat. Sci. Phil., 203, 1823; Compl. Writ, ii, 

 130.) 



This is a shining black species, with yellow margin to the thorax 

 and wing covers. It is evidently a scavenger. The digestive tube is 

 long and coiled like that of a tadpole. It is commonly filled with 

 a brown matter, largely granular and unrecognizable, among 

 which are numerous diatoms, desmids, and fragments of filamentous 

 alga). 



Moderately common in Willow Slough and Cedar Creek. 



Beorsus pcmtheri'tius, Lee. 



(LeConte, Proc. Acad. Nat. Sci. Phil., vii, 3G4, 1855; Horn, Proc. 

 Am. Philos. Soc, 1873, 122.) 



