COLEOrXERA. PARNIDjE. 119 



much confused as regards its affinities ; Fabricius having called it a 

 Pimelia, and Panzer a Trox. Its tarsi are only 4-jointed, but the 

 structure of the parts of the mouth (see Guerin, Icon. Insectes, tab. 20. 

 f. 5.) clearly proves its relationship with the Helophoridse and Elmides. 

 The anterior tibiae are slightly dilated and notched. This insect is 

 occasionally found under stones in running streams, but is more fre- 

 quently observed * in damp earth, with which sometimes the insect 

 is completely coated ; but it is evident that this cannot be for con- 

 cealment (as Kirby and Spence, vol. ii. 258., imagine with respect to 

 some other Insects placed by them in this genus, but belonging to 

 Syncalypta Dillw.), because it is but rarely that this is the case, and 

 consequently cannot be the natural economy of the animal, only hap- 

 pening when it has by chance found its way into soft muddy ground : 

 this coating of mud, when dry, may be scaled off the insect, all the 

 markings of which may be observed on its inner surface. 



The Continental genus Macronychus MxxWex is composed of a single 

 species, M. 4-tuberculatus, a minute aquatic insect, found in the middle 

 and south of Europe. The legs are very long ; the antennae very 

 short, and, according to Latreille and Dufour, 6-jointed, the terminal 

 joint being long and oval, thus approaching, in their irregular con- 

 struction, the antennae of some of the smaller Helophoridae. We 

 are indebted to Messrs. L. Dufour, and Contarini for memoirs upon 

 this interesting insect (figured by Guerin, Iconogr. pi, 20. f. !•., and 

 Germox, Fmm. Ins. Eur.]). \0.^. i The body appears to be clothed 

 beneath with a fine silken coat ; but it is impossible, even with 

 lenses, to discover the hairs of which it must be composed. The 

 males, according to M. Dufour, are entirely apterous, and the females 

 occasionally furnished with fully developed wings; at other times, 

 however, these organs in this sex are very small, and unfit for flight. 

 They are found in running water, appearing to prefer the underside of 

 stones, and especially upon floating wood, burrowing beneath the bark ; 

 their movements are very slow, like those of the Elmis. When taken 

 out of the water they do not survive more than two or three hours. 

 M. Dufour was unable to ascertain in what manner respiration is ef- 

 fected in these insects ; he, however, as well as M. Contarini, noticed 

 a small bubble of air occcasionally affixed to the extremity of the ab- 



* According to M. Wesmael it is always found on the surface of the ground, its 

 body being entirely glabrous, and consequently unable to retain a coating of air 

 when immersed under water. 



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