154 THE ENTOMOLOGIST. 



appear about the central shadow, such as accompany the move- 

 ments of the legs. 



Gerris can also, by a powerful stroke of one of the inter- 

 mediate legs, perform side-movements with perfect ease, and 

 even turn right round, executing strategic movements to the rear 

 with great agility. 



The other active movement is the leaping, whereby the bugs 

 tear themselves loose from the surface of the water and make a 

 spring up into the air. According to Meinert, G. lacustris 

 (Linn.), Stal, can leap a couple of inches on the water, but on 

 dry land it exceeds this to some extent, springing to a greater 

 height, with increased rapidity, and with more continuous move- 

 ment ; one often finds on a hunting excursion that these bugs 

 can leap right out of the net. 



Gerris does not, as a rule, voluntarily enter beneath the 

 surface of the water, but it is evident that its usual position 

 must expose it to the frequent danger of being overwhelmed by 

 sudden squalls, or other disturbances, and swamped. The 

 short, close, velvety pubescence with which they are usually 

 almost completely covered forms —if it be in good and clean con- 

 dition — an investment well-nigh impervious to water,* and they 

 are thus able to rise to the surface unharmed, breaking the 

 surface-film t with some little degree of effort. 



(To be continued.) 



NOTES ON AMERICAN BEES. 



By T. D. A. Cockerell, 



Professor of Entomology, New Mexico Agricultural College. 



(Concluded from p. 129.) 



Colletes nautlanus, n. sp. 

 $ . Length about 9| nrillim., rather broad and compact, shining 

 black. Head broader than long, inner orbital margins quite strongly 

 concave ; face with short white pubescence, rather dense and strongly 

 plumose at the sides ; clypeus with rather strong punctures, more or 

 less running into striae ; vertex with sparse punctures of two sizes ; 

 many black, strongly plumose hairs behind ocelli ; cheeks with white 

 pubescence ; antennae short, entirely black, scape punctured ; clypens 



* The elytra are provided with short close hairs along the nervures, but, 

 despite this, thej' are apt to become soaked and unmanageable when swamped 

 with water ; and this is one of the reasons why I have considered (ante, 

 p. 109) that apterous forms will tend to supplant the others. In some 

 macropterous aud brachypterous individuals I have examined, pubescence is 

 scarcely developed at all on the dorsal surface of the abdomen. 



f See Miall, I. c. pp. 12-15 ; Scourfield, 1894, in Journ. Linn. Soc. 

 Lond. xxv. pp. 1-19, PL 1 & 2. 



