^^~^^ ZOOGENESIS '^^^^ 



their "queens" and one or more forms of female 

 * 'workers . " In the white-ants or termites the various 

 "castes" are both male and female. 



In a few butterflies the females are invariable, but 

 the males are divisible into local races. In the com- 

 mon black swallowtail of the eastern states the males 

 are much more variable than the females, and show a 

 tendency to divide into local races which is not seen, 

 or at least seen not so clearly, in the females. 



Another form of geographical variation which is 

 well illustrated by the butterflies is variation affecting 

 some, most, or even all, of the animals of a certain 

 type in a particular region. 



For instance on the island of Celebes very many of 

 the butterflies, including at least some in all the larger 

 groups and all but one of the local swallowtails, have 

 the fore border of the fore wings very strongly curved 

 with a distinct elbow near the base. These butterflies 

 are in no way related to each other, but each is related 

 to a corresponding form in the Malay region which 

 has the usual form of wing. 



In tropical America very many butterflies, included 

 in all but two of the larger groups, have wings of 

 very curious form, the fore wings very long and 

 broadly rounded at the tips and the hind wings 

 very small. 



The American Aristolochia swallowtails all differ 

 from those of the Old World in having the sinus of 

 the fifth tarsal (foot) segment, in which the claws 

 are inserted, much less extended. 



With the exception of two species, one from the 



[139] 



