18lU.] 



249 



8. In this system, as we have seen, the Lepidopters are classified as 

 " perterrestrial" and the Hemipters (Heteroptera) as " mostly terres- 

 trial." But the larvae of some Lepidoptera are aquatic with aquatic 

 respiration, (see Westw. Intr. II. p. 400 and Harris Inj. Ins. p. 476); 

 and those Heteroptera which inhabit the water (Nepidae and Notonec- 

 tidte) breathe through spiracles in all their states and never through 

 branchia). They are not therefore semiaquatic or aquatic, in the sense 

 o-iven to these terms by Prof. Dana. Consequently the Lepidopters 

 should have been classified as " perterrestrial or semiaquatic," and the 

 Hemipters as "perterrestrial." 



9. The Trichopterous larvse (Phryganeina) are said to "spin silk-like 

 fibres from the extremity of the abdomen, or the lip, or both" (p. 30). 

 So far as regards their ever spinning from the extremity of the abdo- 

 men, I doubt this statement very much. It is contrary to analogy that 

 larvre belonging to the same family of insects should spin, sometimes 

 from the mouth like other larvae, and sometimes from the anus like 

 spiders. Westwood says that " they spin from the mouth in the same 

 manner as caterpillars." {Intr. II. p. 62.) I know from personal ob- 

 servation that the larvae of the Ichneumonide genus Bracht/gaster 

 spin from the mouth, having seen a group of them actually engaged in 

 spinning their singular symmetrical masses of cocoons. The only true 

 insect known to spin from the anus, so far as I recollect, is not a larva 

 but a Coleopterous imago — the European Ilijdrophihts j^iceus, which 

 strongly resembles our R. triangularis Say, but is several sizes larger. 

 It would be interesting to know whether the American species has the 

 same remarkable habit. (See Westw. Intr. I. p. 124.) 



Rock Island, Illinois, July 21, 1864. 



