SPHINGIDES. 365 



(porcellus, elpenor, etc.) carrying many generalised characters; other 

 larvae represented by Sphingids (ligustri), Manducids (atropos), and 

 Amorphids (ocellata, etc.), with fewer generalised and some distinctly 

 specialised characters. (3) A more generalised form of pupa in 

 Amorphids ; a more specialised (especially with regard to maxillae) 

 form in the other groups. (4) A highly specialised form of imago, 

 by development of tongue and frenulum, in all the groups except 

 the Amorphids ; an equally highly specialised imago in the 

 Amorphids by the loss of .maxillae and frenulum. Based on different 

 stages— larval, pupal and imaginal — different groupings would result 

 owing to unequal specialisation in these stages, and one can only 

 formulate a general conclusion by the consideration of all the 

 structures. On this ground one is forced to the conclusion that within 

 the group the lines of differentiation have been based : (1) On one line 

 and one only in the larva, viz., the development of that Sphingid larval 

 form that will respond most perfectly to its environment, and in this 

 particular the Amorphids and Sphingids (sens, strict.} come very close 

 together. (2) On two distinctly divergent lines in the pupa and 

 imago, viz., the development (a) in excess, (b) in defect, of the tongue 

 and frenulum, both characters dependent upon whether a swift-flying, 

 nectar-feeding imago or a heavy-flying, non-feeding imago was being 

 evolved. The former (development in excess) has left the greatest 

 mark on the pupa and external appearance of the imago — Sphingids, 

 Sesiids (Macroglossids), etc. — the latter has left less mark on the pupa 

 and imago, and has possibly retained much more nearly the general 

 characters and form of the other organs which have been less affected 

 by the change. Hence one sees within the group two distinct lines 

 of specialisation. (1) Towards the tongueless form (Amorphid). (2) 

 Towards a highly-developed tongue and (its concomitant structure 

 for rapid flight) long, narrow pointed wings (Sphingid). In the 

 latter section we find different degrees of development in the larval 

 structures, which appear to be rather more generalised in the 

 Eumorphids, and more specialised in the Sesiids (Macroglossids), 

 Sphingids (sens, strict.), Manducids and Amorphids. The com- 

 paratively short tongue of the Manducids has nothing in common 

 with the special line of evolution of the Amorphids, but is proved 

 distinctly by the pupa to be a special development of the Sphingid 

 (sens, strict.) tongue by atrophy. 



Based on larval characters Bacot obtains the following group- 

 ings : 



I. 1st stage pale with greenish tinge; a longer or shorter caudal horn on the 

 8th abdominal, bearing tubercles i at summit ; primary tubercles single-haired 

 (except hi on meso- and metathoracic segments, where it bears two hairs) ; shagreen 

 hairs strongly developed, usually on a cone-shaped base (in early or middle instars) ; 

 iv atrophied on the meso- and metathorax ; v atrophied on abdominals ; a pre- 

 spiracular tubercle (? ancestral) on abdominals ; abdominal segments divided into 

 ? 8 subsegments (best seen in stadia 2 — 4). 



A. Dorsal tubercles on meso- and metathorax set in trapezoidal (or oblong) 

 form (i and ii being on separate subsegments) ; an enlarged 1st subsegment (con- 

 sisting of 3 or more of the normal subdivisions) ; the caudal horn less strongly 

 developed than in B (? a good character) ; the hairs simple, hollow (not bifid). 



I. With tumid 1st and 2nd abdominal segments bearing ocellated spots 

 (when adult). 



a. Fairly developed caudal horn . , . , . , Hippotion 



(celerio). 



