INTRODUCTORY REMARKS. 



sent no more than geographical states of the latter ; though to act, 

 always and without discrimination, upon that hypothesis might in- 

 volve errors of a worse kind than the mere insertion (into a Cata- 

 logue) of an occasional form which has been wrongly entered as 

 specific. I believe however that the instances are not very numerous 

 in which an accurate and experienced naturalist would have much 

 difficulty in satisfying himself concerning the proper rank of the 

 various creatures with which he has here to deal ; for the greater 

 number of them are most clearly defined, whilst even in the case of 

 the obscurer ones there are often local considerations by which ap- 

 parent discrepancies may be explained. 



But if we admit the probability that a' small proportion of the 

 forms which are treated in this volume as specific may be but geo- 

 graphical modifications of others which are already known, I must 

 at the same time express my conviction that an overwhelming ma- 

 jority of them are quite in the opposite predicament, and owe next 

 to nothing (so far as their specific features are concerned) to the 

 action of the external influences by which they are surrounded. 

 Especially will this apply to the Euphorbia -infesting group an 

 assemblage of marvellous types which (as lately insinuated) are 

 nearly without a parallel, both as regards the number of the indi- 

 viduals by which they are severally represented, and the greater or 

 less eccentricity of their structure. It is true that a few of the species 

 (if indeed I am correct in regarding them as such) display a certain 

 amount of correlation with the particular kind of Euphorbia to which 

 they are attached. Thus, in the Aphanarthra the development of 

 tubercles on the anterior edge of the pronotum seems, in some 

 mysterious manner, to be connected with the " sweeter," or less 

 pungent, members of that curious race of plants ; for those species 

 which are nourished within the acrid stalks of the E. canariensis 

 have no indication of prothoracic pustules, whereas those which feed 

 on the less caustic, or more palatable, E. balsamifera and regis-Jubce 

 show a decided tendency (more or less expressed) to be armed with 

 them. This however is but a trifling circumstance (although un- 

 doubtedly interesting), and one which leaves untouched the won- 

 derful dissimilarity (inter se) of these Euphorbian types, and their 

 wide divergence from every other organism of the same geographical 

 domain. 



As above stated, however, the vast multitude of quaint and gro- 

 tesque shrubs on which this esoteric assemblage depends for sub- 

 sistence is becoming gradually exterminated. True it is that the 





