THE FAUNA OF SCOTLAND. 3 



Introduction, formed Loi)hyrus and Lyda into a sub-tribe, but 

 he placed the Tentliredina between them and Cimhex and 

 Hylotoma ; though these are so nearly related to Lophyrus that 

 I cannot see how they can be separated in this way without 

 violating many affinities. No doubt, if we regard only the 

 European genera, the evidence in favour of my classification 

 will appear rather weak, and it must be recollected that the 

 Tenthredinidae have only been properly classified according to 

 the Palaearctic forms ; but I say that if we take into considera- 

 tion all the genera of the world, we find then many evidences 

 tending to prove the correctness of my views. Cimhex, Hylotoma, 

 and LojyJiynis, are so sharply cut off from each other by the 

 structure of the antennae, that we must rely on other points to 

 show their relation to the lower groups and to each other. This, 

 I think, is found in the possession of a small appendicular cellule 

 in both the wings, and the presence of spines (none of which are 

 found in Tenthredina), on the tibiae as in Lyda; they seem indeed 

 to indicate that Cimhex, etc., branched off early from some common 

 ancestor, while the Tenthredina and Nematina branched off later 

 from some form allied to Lophyrus.* 



Hylotoma is connected with the Cimbicides through Syzygonia, 

 while Pterygophorus unites it with Lophyrus. Whatever views we 

 may hold regarding the position of Cimhex and Hylotoma, it seems 

 to me very unnatural to place Tenthredo next to Lyda, with which 

 it has no affinity whatever, as is usually done. I regard Tenthredo 

 as more highly organised than Cimhex, which is probably only a 

 remnant of a once extensive family. Size in the Hymenoptera is 

 of no value as indicating the higher systematic position of a 

 genus; rather the reverse. I may here remark that seemingly 

 unimportant structures like spines on the tibiae, appendicular 

 cellules, etc., are of greater value in indicating affinity in this 

 group, because less liable to vary, than other organs of more 

 importance to the animal. And 1 would also point out that it 

 is only (except in Cladius) among the Cimhicina, Hylotomina, and 

 Lophyrina that we find secondary sexual characters developed to 

 any extent, these being in the two last groups very conspicuous. 

 In the Tenthredinidae the possession of numerous joints in the 

 antennae must be regarded as evidence of low development, and 

 consequently of greater antiquity. 



* In this respect Cladomacra and Monoctenus are suggestive. 



