84 THE ENTOMOLOGIST. 



for these appearances. We should be far more inclined to say 

 that the divergence was, in the first instance, the direct result of 

 certain modifying factors of nature, one of which would be tem- 

 perature, whose undeniable effects in changing the aspect of 

 species we have already seen in the temperature experiments. 

 It is easily understood that a factor causing slight divergence 

 during a long period would have less result than a factor causing 

 strong divergence in a shorter. Perhaps the capability of re- 

 action or change is increased when certain individuals, through 

 the influence of natural factors, have been driven from a con- 

 dition of relative stability to one of unstable equilibrium. The 

 probability of this theory is confirmed by certain groups of the 

 Lepidoptera, in their, one might say, explosive change of form, 

 for example, in the tribes of Zygaena and Agrotis. Among 

 plants, the families Hieracium, Rubus, and Rosa seem to be 

 similarly situated. 



[The four plates accompanying Mr. Dadd's translation of 

 Prof. Standfuss's paper are reduced copies of the originals in 

 ' Insekten Borse,' 1899, published by Frankenstein & Wagner, 

 of Leipzig.] 



NAMES OF LEGS OF INSECTS. 

 By G. H. Verrall, F.E.S. 



When will entomologists of the present time correctly name 

 the legs of insects '? 



All entomologists know that insects have three pairs of legs, 

 but after that (in at least Dipterology) they seem to be in hope- 

 less confusion. 



The three pairs of legs are — 



1. Front \egs= Pedes antici. 



2. Middle \egs= Pedes niedii. 



3. Hind legs=Pedes postici. 



For convenience there exist the combinations of — 



o' [Anterior legs=Pe^es anteriores (excluding "jyostici"). 



2 ) 



o* [Posterior \eg8=Pedes posteriores (excluding " antici "). 



Let it be clearly understood that there is only 



One pair of front, middle, or hind legs ; 

 but that there are 



Two pairs of anterior or posterior legs. 

 The above definition, of course, applies to parts, audi as 

 femora, tibiae, tarsi, &c. 



Anterior does not mean front only. 



Posterior does not mean hind only. 



N.B.— American journals please copy. 



