Phylctic Parallelism in Mctamorphic Species. 451 



" shagreened," although it must be admitted that 

 there are exceptions {Vcsperiilio). The genus 

 Ch&rocampa admits also of being based on the 

 form-relationship of its caterpillars, although this 

 is certainly only possible by disregarding the 

 marking and taking alone into consideration the 

 peculiar pig-like form of the larvae. The genus 

 Ac/ierontia t so nearly related to Sphinx, possesses 

 in the doubly curved caudal horn a character 

 common to the genus (three species known M ). 

 Finally may be mentioned the genus Smerinthus, 

 of which the larvae, by their anteriorly tapering 

 form, their shagreened skin and almost triangular 

 head with the apex upwards, their simply curved 

 anal horn, and by their seven oblique stripes on 

 each side, constitute a genus as sharply defined as 

 that formed by the moths. 



Although in all the systematic divisions hitherto 

 treated of there are cases where the form-rela- 

 tionship of the larva does not completely coincide 

 with that of the imago, such incongruences are of 

 far more frequent occurrence in the smallest sys- 

 tematic group, viz. species. 



The larvae of two species have very frequently 

 a much nearer form-relationship than their ima- 

 gines. Thus, the caterpillars of Smerinthus 



14 [The larva of Acherontia Mar/a, figured by Butler (see 

 note 50, p. 262), possesses the char, cteristically recurved horn . 

 that of Ach. Medusa figured by the same author, does not 

 appear to possess this character in any marked degree. R.M.] 



G g 2 



