. Manchester Memoirs, Vol. xliii. (1899), iVi?. 11. 15 



ship, as evidenced by the degrees of development 

 attained, carefully investigated and compared with other 

 characters. I will illustrate my meaning by one case only 

 before I proceed to investigate carefully the case of 

 Calinaga. 



In the Indo-Malayan region, in Sikkim for instance, 

 is to be found a well marked genus of the Papilionidce, 

 the representatives of which, being nauseous, are mimicked 

 by those of a similarly marked but morphologically 

 widely separated genus. In certain cases, pending the 

 revision of Papilionid genera by the Hon. Walter 

 Rothschild, I shall only refer to the species in their 

 specific character. It will, however, suffice by way of 

 argument. The first to which reference may be made is 

 the nauseous Papilio philoxenus (Moore's genus Byasa) 

 which is mimicked by Bootes West. Now, without taking 

 into account the other well-marked characters of the two 

 genera, such as the general neuration of the wings, the 

 shape of the discoidal cell of the hind wings, the large 

 head of Bootes as compared to that of Philoxenus, the 

 presence of an anal fold in the hind wings of the male 

 Philoxemts and its absence in Bootes, take the evidence of 

 one single character, a character too little appreciated and 

 recognised, viz., the form of the basal cell; and, however 

 similar the two species may be in general appearance (a 

 similarity to which Bootes owes its existence), it is at once 

 very easily seen from this evidence alone that they are 

 representatives of two genera. Byasa philoxenus has a 

 peculiarly shaped basal cell having the portion between 

 the precostal and the costal nervures (the distocostal limb) 

 of a markedly arched conformation and relatively longer 

 than that of Bootes, and the portion between the base 

 of the wing and the point where the subcostal originates 

 (the mediocostal limb) relatively shorter than that of 



