THE CANADIAN ENTOMOLOGIST. 15 



NOTE ON THE LARVAL ORNAMENTATION OF THE N. AM. 



SPHINGID^. 



BY A. R. GROTE. 



In my " Hawk Moths of North America," I have assumed that the 

 caudal horn is a prolongation of the skin itself, stiffened by chitine (p. 41). 

 It supports a bristle, or pair of bristles, and Dr. W. Miiller, whose valu- 

 able work on the Nymphalidce of South America in their larval stages 

 (Zoologischen jahrbuchern, 1886.) I have noticed in these pages, figures 

 the horn of Dilophonota, p. 249, and regards it as a prolongation of the 

 base supporting the two normal bristles of the eleventh segment. We may 

 assume that the caudal horn is a later development, and that the sur- 

 mounting bristles were originally sessile as in the Attacince. The bristles 

 themselves may have disappeared, and the horn itself, the prolongation of 

 the base, remain. I would draw attention to this character as supporting 

 generally my arrangement of the fiimily. The thoracic "horns" of 

 Ceratomia are probably homologous with those of Citheronia. This 

 character, together with the comparatively sunken head and soft brown 

 colors of the moth allies Ceratomia with Triptogon, as I have pointed 

 .out. Dr. Wm. Miiller concludes that the caudal horn of the Hawk Moths 

 is the remains of what was once a system of bristles, and that there is a 

 perfect homology with the Saturnidce. This entirely agrees with my 

 idea as to the derivation of the family, which may have thus been thrown 

 off from the Spinners in a parallel direction with the Ccratocampince, 

 The modern Smerinthince remain as the descendants of intermediate 

 phases, the ocelloid spots and colors of the moth are retained. In this 

 sense they are synthetic characters appearing in the other three or four 

 groups which are to be referred to Smerinthoid affinities. The relatively 

 small and sunken head, and the square prothoracic parts, the pectinate 

 antennte, are probably low characters in the Hawk Moths, recalling the 

 Bombyces. In this view the shape of the body in Hemaris and allies is 

 a point of widest departure, and warrants the position I assign to the 

 Macroglossmce. The method of pupation needs further elucidation. It 

 must be studied in this group, with regard to the physical nature of the 

 surface. Probably the cocoon is older than the absence of silk, the 

 tendency to spin silk appearing by reversion in species today where it 

 seems to have become gradually lost as a character. The change to 

 pupation in the earth may have had some relation to changes in th^ sur- 

 face conditions in past ages, 



