186 [November 



find that the species are somewhat nearly allied, while our species oflPers 

 differences in the structure of the antennae and in the shape of the se- 

 condaries, especially in the structure of their costal margin. The form 

 of the palpi and position of the head, very nearly correspond in the 

 two species. We express the opinion that dissectional study will oblige 

 the separation of Smerinthus modestus from the typical species first cited 

 in our Catalogue, while for the present we leave it in the genus in 

 which it was placed by Dr. Harris. 



CRESSONIA, nov. gen. 

 A genus hitherto confounded with Smerinthus and Poli/ptijchus^ by 

 authors; the single North American species distinguished by the fol- 

 lowing characters and without a described representative in the Old 

 World : 



The antennae are rather short and blunt; in the male, doubly bi-pec- 

 tinate, the pectinations stout and well developed, produced from be- 

 neath the antenna! stem; in the female, the antennas are simple. The 

 small head is freer from the thorax than in Smerinthus, and neither 

 so sunken in the prothoracic parts or so depressed. The acuminate 

 palpi are longer, more freely scaled, held free from and exceeding the 

 "front," divergent at the tips in the male; the clypeal squammation 

 forms a produced ridge. The prothorax is squarerin front; above, the 

 thoracic surface is more flattened, not roundedly elevated as in Smerin- 

 thus. The anterior wings are broad and large, 

 excavate, between the nervules, along the ex- 

 ternal margin in the female, even, in the male. 

 The "veins" are slight, the nervules more bent 



downwards and curvilinear than in Smerinthus, 

 Anterior wmg of 9 Ores- . , , , i mi 



soni'a, natural size. internal angle less esserted. Ihe posterior 



wings are full and rounded, not " cut away" before the 

 anal angle on external margin — the latter emarginate in 

 both sexes — differing prominently from Smet-inthus in 

 their general shape, being more rounded and not pro- 

 duced apically; the costal vein is basally divaricate, os enorwingo 

 t J ' _ _ •' 'J Cressonia, na- 



the nervules long, curvilinear and divergent. The ab- tural size. 



domen is slender and elongate, and affords distinctive 



characters compared with that part in Smerinthus. In 



the male it is very long and slender, the anal segment 



Posterior^viugofP™^'i*^^*^ with a terminal and lateral sub-tufts, giving a 



Smennthus, [ge- i^l.Tp^Ytlto, appearance to the terminal segment, which is 



minatus) natu- . . . . , p 



ral size. characteristic. 1 his genus differs importantly from xS'. 



