244 Stiidies in the Theory of Descent. 



and thus corresponds to the first stage of S. Populi. 

 This species may possibly retain in its ontogeny 

 a stage in which the oblique stripes are also absent, 

 whilst the subdorsal line is present. From the early 

 disappearance of the subdorsal line in the species 

 of Smerinthus, we may venture to conclude that 

 this character appeared at an early stage of the 

 phylogeny, whilst the oblique stripes represent 

 a secondary form of marking, as shall be further 

 established subsequently. 35 



85 [The larvae of four other species of this subfamily have since 

 been made known through Mr. Butler's figures. Smerinthus 

 Tatarinovii, Menetries (loc. cit. PI. XC., Fig. 16), from Japan, 

 is " pale sea-green, tuberculated with white, with seven lateral, 

 oblique, crimson-edged white stripes." There is no trace of 

 the subdorsal line shown in the figure, so that this species 

 thus appears to be in the third phyletic stage of development. 

 Smerinthus Planus, Walker, from China (loc. cit. PI. XCIL, 

 Fig. n), is "pale green, with white or yellow lateral stripes." 

 A trace of the subdorsal line remains on the front segments, 

 thus showing that the species is in the second phyletic stage 

 of development. Triptogon Roseipennis, Butler, from Hakodadi 

 (loc. cit. PI. XCL, Fig. 6), is represented as yellow, with seven 

 oblique white stripes, with large irregular triangular red spots 

 extending from the anterior edge of the stripes, nearly across 

 each segment. It is probably in the third phyletic stage. 

 The Indian Polyptychus Dentatus, Cramer (loc. cit. PL XCL, 

 Fig. 10), is "bluish-green at the sides, with oblique purple 

 stripes, with a broad, dorsal, longitudinal, golden-green band, 

 bordered by subtriangular purple spots, one above each stripe." 

 The dorsal band is bordered by coloured stripes, which maybe 

 the subdorsal lines ; but the position in which it is figured, and 

 its very different mode of coloration, make it very difficult to 

 compare satisfactorily with the foregoing species. The genus 

 Ambulyx is closely allied to the SmerintJimce, and the two 



