Ixv 



trace of structural relationship (except that which makes them mem- 

 bers of the same family) is entirely lost. This extreme variability is 

 not of common occurrence in the class Tnsecta, or even in the 

 Animal Kingdom, at least to the extent of prevailing over an entire 

 family containing 8000 species. It may well lead us to reflect on the 

 principle which has attended the process of origination of forms, and 

 lias led to the retention, unaltered, of portions of their structure, whilst 

 the rest have become modified, thus enabling naturalists, in the 

 majority of cases, to classify them. This principle is the great ally 

 of the systematist, although he troubles himself so little with inquiry 

 into its nature. It is this which has retained the internal bony 

 skeleton in the class Vertebrata, whilst all the rest of the structure is 

 changed in one or other of the component families — organs of respi- 

 ration and locomotion, limbs, skin, as well as clothing and habits. If 

 we except the two or three primary divisions of the Longicorns, there is 

 no portion of structure which retains a given form throughout a number 

 of species, sufficient to form a well-defined genus of ordinary length or 

 a group of genera. As M, Lacordaire expresses it, " Les caracteres les 

 plus importants s'alterent, s'effacent et disparaissent, avec une rapidite 

 desesperante." It surely is not too much to say that if such instability 

 were a general feature of the Animal and Vegetable Kingdoms, classi- 

 fication would have been impossible, and Linnaeus himself would have 

 striven in vain ; yet its existence throughout the extensive secondary 

 groups of the Longicorn Coleoptera shows, that stability of some struc- 

 tural characters and modification of others — in other words, the forma- 

 tion of natural genera — is not an invariable accompaniment of the 

 process of creation, and I think the subject has not yet received all 

 the attention it deserves or will eventually receive. 



One of the works to which I alluded as bearing on the question of the 

 origin of species is a treatise entitled " Entomologische Beitrage zur 

 Beurtheilung der Darwin'schen Lehre von der Enstehung der Arten,'* 

 published early in the past year, in the concluding part of the 

 'Berliner Entomologische Zeitschrift' for 1867, at page 327. The 

 writer, Herr von Kieseuwetter, is an author of wide reputation, and 

 belongs to what I think may be fittingly called the Berlin school of 

 Entomologists — a class who have distinguished themselves more 

 especially as rigid systematists, being known for their acute and 

 profound investigations into the characters of varieties, species, genera, 

 and higher groups, in their application to classification. Some of the 



