classification of the Ade^jhaf/a. 65 



they can be accepted. In the case of the Siagonini, for 

 instance, Horn departs from the views of Chaudoir as to 

 the mesosternal structure, and states that the middle 

 coxal cavities are closed externally by the junction of the 

 middle pieces of the meso- and meta-thoraces, and that 

 Schiodte, Schaum, and Chaudoir have been deceived in 

 their supposition that these pieces are separated by the 

 interposition of the mesothoracic epimeron. To deter- 

 mine this he relies on macerating the specimen in 

 caustic potash, but this appears to me a very unsafe 

 proceeding, — and for this reason,— the mesosternum of 

 Siagona is a very peculiar one, and the pieces forming it 

 are all soldered together, but they are traversed by some 

 prominent ridges, along which the chitinous substance is 

 very much thicker than elsewhere, and these ridges may 

 longer resist the action of the potash, and so give rise 

 to a deceptive appearance of sutures ; moreover, after 

 having made a special dissection of the largest Siagona 

 (S. dejeani) and removed the metathoracic episternum, 

 it appears to me clear that the suture separating the 

 middle piece of the mesosternum from the side piece can 

 be undoubtedly traced, and that Chaudoir, Schaum, and 

 Schiodte were correct in considering that the meso- 

 thoracic epimeron separates the middle sternal pieces. I 

 think, therefore, we should be reluctant to acce^Jt the 

 evidence of preparations that have passed through so 

 serious an ordeal as that of maceration in caustic potash, 

 in opposition to the direct evidence from unaltered 

 specimens. 



In the case of many of the tribes Dr. Horn adopts, 

 he makes use of the same names for them as have been 

 used by his predecessors, although giving to those names 

 a widely different extension or meaning. This plan 

 is that usually adopted by zoologists, but it is accom- 

 panied by the great disadvantage that it gives to classi- 

 fications a false appearance of accord and permanence, 

 and also, by giving to the names the sanction of long use, 

 tends to make them appear in the eyes of many of more 

 importance than they are in fact. Indeed, I myself am 

 of opinion that classification of the groups superior in 

 complexness to genera is at present so extremely far 

 from approximation to the actual facts, and that these 

 groups will thus probably in future assume a totally diffe- 

 rent form, that we should do well to refrain from giving 

 them names at all, contenting ourselves with the simple 



TRANS. KNT. SOC. I8b'2. PART I. (APRIL.) K 



