52 JOHN B. SMITH. 



vein seven, than to the " subcosto postapical nervule," and where 

 the number of veins is so uniform and the rehative position of the 

 veins so constant as it is throughout the Lepidoptera, the numeric 

 system has decided advantages over the other in simplicity. 



I cannot see the advantages either in speaking of nervules and 

 nervures, making those veins reaching the base nervures, Avhile those 

 which do not reach the base are tiervides. 



Clemens' names for the veins are given above ; his names for the 

 interspaces are as follows : 



Apical, between 7 and 8 ; postapical, between 6 and 7 ; disco-cen- 

 tral, between 5 and 6 ; medio superior, between 4 and 5 ; medio cen- 

 tral, between 3 and 4 ; medio posterior, between 2 and 3 ; submedian, 

 between 1 and 2 ; internal, below^ vein 1. 



The legs are variable in length, strength and armature, both as to 

 spinulation and the ordinary spines of middle and hind tibiae. 



The genitalia are of a peculiar type, so far as I am aware not 

 found with any constancy in any other group of the order The 

 supra-anal plate and the normal supra-anal hook of the Heterocera 

 is here modified into a structui-e that may be roughly compared 

 to one of the great claws of a lobster. There is a decided tendency 

 in the genus Hemaris to a division of the supra-anal hook, which in 

 Dilophonota and Argeus is completed, the hooks being separated some- 

 what as in some of the Saturiiiidce, while here the plate in one of the 

 genera, at least, is double. 



I have been able to examine the genitalia in inost of the species 

 here treated, and have given figures of the supra-anal plates and 

 side pieces. In addition there are one or two other variable struc- 

 tures, as the penis sheaths, which I have not been able to examine 

 carefully, and which may in future afford characters of value. 



The habits of the imago are diurnal or crepuscular, some species 

 flying in the hottest sunshine, others and the great majority of the 

 species in the early evening, in the twilight and just at dusk ; a few- 

 fly to light or come to sugar, while in the Smerinthiuce the species 

 are rarely taken, except at light. Their habits are thorouglily Bom- 

 hijciform. 



The larva of the Sphingldxe are as readily distinguished as are the 

 imagos. They are usually large in size, solitary feeders as a rule, 

 green in color in the majority of instances, often with oblique lateral 

 stripes ; generally they are furnished with a prominent caudal horn, 

 in some few forms lost in the latter stages and then replaced by a 

 shinin"- lenticular tubercle. 



