Jan., '06] ENTOMOLOGICAL NEWS. 3 



without much difficulty. The second and third pair of pedes 

 are moved alternately and quite rapidly, the second pair row- 

 ing while the third recovers, and the second recovering while 

 the third gives a vigorous stroke. The femora cross each 

 other when the second pair gives the propulsive stroke and 

 are widely separated when it reaches the extreme of the 

 return, the third pair being at the end of the backward move- 

 ment. The stroke of the second pair of legs in all likelihood 

 merely helps to conserve the momentum imparted by the 

 powerful third pair, which does all the work. The second 

 pair is but feebly set with hairs while the third is provided 

 with abundant fringes along the edges of the tibse and tarsi. 

 As in other waterbugs, these hair-fringes fold back in the re- 

 turn and expand on the propulsive stroke. Belostoma gen- 

 erally swims back up, but at times it moves abdomen up. On 

 land it runs with considerable celerity and ease, employing the 

 two posterior pairs of legs. 



Pelocoris I have not succeeded in observing closely. This 

 bug moves its legs so rapidly that they can scarcely be fol- 

 lowed. However, the third pair is mainly used in swimming, 

 and the legs are moved together. It runs quite briskly on 

 land and in the water, its natural home, it creeps among the 

 water plants. 



The only Nepid I have had the opportunity to observe is 

 Ranatra quadridentata Stal., of which I keep a few living ones 

 every summer. I have watched this bug swim repeatedly, 

 and as its motions are quite slow, it has been possible to ana- 

 lyze them much more easily than those of the others. As I 

 have elsewhere noted, Ra?iatra employs in locomotion only 

 the second and third pair of legs, the first being strictly rap- 

 torial and prehensile. Further, since Ranatra is not one of 

 the swimming waterbugs (in fact its affinities are with land 

 forms as pointed out by Schibdte),* its locomotion under 

 water is rather awkward, to say the least. The pedes move 

 alternately back and forward, the second pair alternating with 

 the third, much as in Belostoma, but in a much more leisurely 

 manner. Again, as in Belostoma, at one extreme of the 



• Ann. Nat. Hist. (4) vi., 1870, p. 225, etc. 



