446 Studies in the Theory of Descent. 



which was also formerly (Godart, 1819") united 

 with Vanessa, the larvae bear branched spines on 

 all the segments, the head and prothorax in- 

 cluded. 



It is possible to go still further and to separate 

 two species of Vanessa as two new genera, although 

 they have hitherto been preserved from this fate 

 even by the systematists most given to " splitting." 

 This decision is certainly justifiable, simply be- 

 cause these species at present stand quite alone, 

 and the practical necessity of forming a distinct 

 genus does not make itself felt, and this practical 

 necessity moreover frequently comes into conflict 

 with scientific claims : science erects a new genus 

 based on the amount of morphological difference, 

 it being quite immaterial whether one or many 

 species make up this genus ; such an excessive 

 subdivision is, however, a hindrance to practical 

 requirements, as the cumbrous array of names 

 thereby becomes still further augmented. 



The two species which I might separate from 

 Vanessa on the ground of their greater divergence, 

 are the very common and widely distributed V. 

 lo and Antiopa, the Peacock Butterfly and the 

 Camberwell Beauty. In the very remarkable 

 pattern of their wings, both show most marked 

 characteristics ; lo possesses a large ocellus on 

 each wing, and Antiopa has a broad light yellow 

 border which is not found in any other species of 

 11 Encycl. Meth. ix. p. 310. 



