498 GEOGRAPHICAL ZOOLOGY. [part iv. 



LONGICOEXIA. (1,488 Genera, 7,576 Species). 



The elegant and admired group of the Longicorn Beetles, is 

 treated by continental authors as a single family, consisting of 

 three sub-divisions — the I'rionidte, Cerambycidoe, and Lamiidae 

 of English entomologists. These are so closely related, and are 

 so similar in form, habits, and general distribution, that it will 

 be best to consider the whole as one group, noticing whatever 

 peculiarities occur in the separate divisions. The endless 

 structural differences among these insects, have led to their 

 being classed in an unusual number of genera, which average 

 little more than 5 species each ; a number far below that in any 

 of the other families we have been considering, and probably 

 below that which obtains in any of the more extensive groups 

 of animals or plants. This excessive subdivision of the genera, 

 a large number of which consist of .only one or two species, 

 renders it difficult to determine with precision the relations of 

 the several regions, since the affinities of these genera for each 

 other are in many cases undetermined. A group of such 

 enormous extent as this, can only be properly understood after 

 years of laborious study ; we must therefore content ourselves 

 with such results as may be obtained from a general survey of 

 the group, and from a comparison of the range of the several 

 genera, by means of a careful tabulation of the mass of details 

 given in the recent Catalogue of Messrs. Gemminger and Harold 

 and the noble work of Lacordaire. 



The proportionate extent of the three families of Longicorns is 

 very unequal ; the Prionidss comprising about 7 per cent., the 

 Cerambycidae 44 per cent., and the Lamiida? 49 per cent, of the 

 total number of species ; and the genera are nearly in the same 

 proportions, being almost exactly 10, 40, and 50 per cent, of the 

 whole, respectively ; or, 135 Prionidae, 609 Cerambycidae, and 746 

 Lamiidse. The several regions, however, present marked differ- 

 ences in their proportions of these families. In the two North 

 Temperate regions, the Cerambycidae are considerably more 

 numerous than the Lamiidte, in the proportion of about 12 to 



