45 2 Studies in the Theory of Descent. 



Ocellatus and S. Populi are closely allied in struc- 

 ture, marking, and colouring, whilst the moths in 

 these two last characters and in the form of the 

 wings are widely separated. 16 Judging from the 

 larvae we should expect to obtain two very similar 

 moths, but in fact both Populi and Ocellatus have 

 many near allies, and these closely related species 

 sometimes possess larvae which differ more 

 widely than those of more distantly related species 

 of imagines. 



Thus, in Amur-land and North America there 

 occur species of Smerinthus which closely resem- 

 ble our Ocellatus in colour, marking, and form of 

 wing, and which possess the characteristic large 

 blue ocellus on the hind-wings. 5". Excczcatus is 

 quite correctly regarded as the representative 

 American form of our Ocellatus, but its caterpillar, 

 instead of being leaf-green, is of a chrome-yellow, 

 and possesses dark green instead of white oblique 

 stripes, and has moreover a number of red spots, 

 and a red band on the head in brief, in the very 

 characters (colour and certain of the markings) in 

 which the imagines completely agree it is widely 

 different from Ocellatus. It appears also to be 

 covered with short bristles, judging from Abbot 

 and Smith's figure. 16 



Just in the same way that the species having 



11 [See note 28, p. 233. R.M.] 



" IJH. fit. PI. XXV. [This species is referred by Butler to 

 the genus Faonias, Hiibn. R.M.] 



