\H'j3.\ 233 



leaves did not facilitate their discrimination. Microvelia pygmcsa, 

 which was also present in great numbers, conld be segn without any 

 difficulty, though so much smaller. Promiscuous skimming of the 

 surface with a water net, however, yielded a plentiful supply of the 

 previously \\\\\^i\Ae Mesovelia. With the exception of a single winged 

 specimen, all that I found (probably as many as 150) were undeveloped ; 

 of the much more abundant Microvelia, I found eight developed 

 examples. I kept a number of Mesovelice under observation in a glass 

 jar for three weeks. When disturbed, tliey were extremely lively, 

 darting about over the leaves of Potamogeton and the water with equal 

 ease and extraordinary agility : in fact, they moved under such circum- 

 stances far more rapidly than any other of our aquatic Semiptera. 

 On the water they maintain the same position as on the leaves, and 

 their motion is in both cases an insect's ordinary walk or run, i. e., 

 the corresponding legs of the opposite sides are moved alternately, as 

 in Hydrometra, and not simultaneously, as in Qerris The position on 

 the water is intermediate between that of Hydrometra, in which the 

 body is kept high above, and that of Microvelia or Velia, in which it 

 is close to, the surface, and as with Hydrometra, only the tarsi are in 

 actual contact with the water. When resting, they often assumed a 

 frog-like position, the male especially sloping its body, with head m 

 air, and hinder extremity almost touching the leaf on which it was 

 standing. They often rested also on the sides of the jar, climbing up 

 just above the water level, and remaining there, out of contact with 

 the water, but with head turned towards it, so as to be ready on the 

 slightest alarm to dart down to a position of greater freedom. 



They are carnivorous in tastes. I kept them supplied with a 

 variety of small insects, and on different occasions saw them sucking 

 a Smynthurus, a Cramhus, a Ghalcid, and, apparently most unpromising 

 of all, a Hydrometra. The rostrum is extremely flexible, and in feeding 

 is bent into whatever position enables the insect to reach the most 

 easily assailable parts of its prey. The setae do not seem to be power- 

 ful enough to pierce such a hard integument as covers the greater 

 part of the body of Hydrometra, and in this case, therefore, advantage 

 was taken of the softer skin which occurs at the junction of the 

 coxse with the body, and the rostrum was thrust in there. One of the 

 females, after taking a long draught of Smynthurus blood, walked to 

 the edge of the floating leaf on which its prey was lying, dipped its 

 rostrum into the water, and then rubbed it with its fore-legs. As it 

 is evidently of the utmost importance that the rostral channel should 

 be kept open and clear for the passage of liquid, I have little doubt 



