21C LONGIOORXIA. [Lo 



first and second joints of the posterior tarsi), claws almost always simple, 

 but rarely cleft or appendiculate. The colouring of the species is very 

 variable, and in some of the exotic species is very handsome ; it appears, 

 however, to be rarely metallic. 



The Longicornia are closely connected with the Chrysomelidse, and 

 although no one is likely to confuse the members of the two groups, 

 yet the difference between them is hardly capable of beinj? expressed 

 satisfactorily in words. Dr. Horn (Classification of the Coleoptera of 

 North America, p. 269) says that "so far the essential difference 

 between the Tetramera, of which the larvae feed upon wood, and those 

 feeding upon cellular vegetable tissues, has eluded observation. We 

 can merely at present observe that a slight approximation to it seems to 

 be made in the fact, that in the Cerambycidae there is a tendency in 

 the epimera of the metathorax to extend to the sides of the ventral 

 segments, while in the ChrysomelidaB the first ventral segment is pro- 

 longed forwards at the sides to meet the metathorax, thus showing 

 probably a lower, though necessarily more recent type, which could 

 have existed only since the development of the higher broad-leaved 

 plants," 



The members of this group, owing to their habits of life in the larval 

 state, are probably among the most archaic of the Coleoptera ; they can 

 live a long time within the trunks of trees in which they take up their 

 abode, even if they are immersed in water, and are, of course, to a great 

 extent protected against external enemies ; the chief collector and 

 describer of the group, Mr. H. W. Bates, in commenting upon the vast 

 amount of different forms belonging to the family, remarks as follows :* 

 " It is one of those groups of insects in which nature, in striving after 

 strong individuality in the species, seems to have changed or adapted 

 those parts of structure upon which we rely for characters of genera 

 and groups of genera. The family, too, is found throughout all parts 

 of the world where woody vegetation exists, and has endured, probably, 

 under the same laws of modification, throughout long geological periods. 

 The diversity of specific forms seems endless, running into infinite 

 varieties of grotesque, ornamented, and extraordinary shapes; and 

 nearly every species has structural peculiarities for its specific characters ; 

 so that in no family can genera be made so easily and numerously as 

 here. Analysis is too easy, and has already been pushed, perhaps, to 

 too great an extent." 



The larvae of the Longicornia are large fleshy insects, which, as a rule, but 

 not always, have the prothorax much enlarged in comparison with the suc- 

 ceeding segments, and are more or less gradually narrowed behind ; the meso- 

 aud metathorax arc often very short; (he abdominal segments are nine in number, 

 and the anal segment is rounded and continuous with the body, presenting the 

 appearance of a tenth segment; the head is corneous and depressed, armed with 



* Contributions to an Insert. Fauna of the Amazon Valley. Coleopteru, Longi- 

 cornes. Part I., Lamiaires, pp. o-G. (Annals and Magazine of .Natural History, 1S61 ) 



