DYTISCID^. 



435 



ligula ; /, mentura ; g, prosternum, front, and 7i, side view ; ^■, 

 under side of the rest of tlie bod}^, showing the six ventral seg- 

 ments of the abdomen ; J, anterior tarsus : from Horn) found 

 in Northern California, is the sole representative of this family 

 and differs from the preceding family in the metasternum be- 



h d j i 



m 



Fig. 379. 



ing truncate behind, and not reaching the abdomen. A. inso- 

 lens Lee. is an anomalous form, being subaquatic, and in its 

 structure and habits connecting the Cardbidce with the suc- 

 ceeding family. » 



Dytiscid^ McLeay. The Diving Beetles, or "Water Tigers, 

 are oval flattened elliptical beetles, which differ from the Ca7'- 

 abidce in the form of the hinder coxae, which are very large, 

 touching each other on the inner edge, and externally reaching 

 the side of the body, entirely cutting off the abdominal seg- 

 ments from the metathorax, while the oar-like swimming legs 

 are covered with loug hairs, and the hinder pair are much flat- 

 tened. The larvae are called "water tigers," being long, cy- 

 lindrical, with large flattened heads, armed with scissor-like 

 jaws with which they seize other insects, or snip off the tails 

 of tadpoles, while they are even known to attack young fishes, 

 sucking their blood. They are known to moult several times, 

 four or five days intervening between the first two periods of 

 moulting, and ten days between the latter. The body ends in 

 a pair of long respiratory tubes, which they protrude into tlic 

 air, though eight pairs of rudimentary spiracles exist. When 

 about to transform the larva creeps on to the land, constructs 

 a round cell, and in about five days assumes the pupa state, 

 and in two or three weeks the beetle appears, if in summer, or 



