NORTH AMERICAN LEPIDOPTERA. 117 



Chrerocampa has a very long abdomen ; narrow, graceful wings 

 and slender antennae, with a small hook at tip. It finds a close ally 

 in ^Ellopos. 



Argem is allied to Chcerocampa by the slender antennae, with a 

 somewhat longer hook at tip. The head is large and prominent, and 

 the body slender and graceful. The wings are rather narrow, the 

 excavation of outer margin well marked. 



The other genera have the antennae fusiform, with a long, recurved 

 hook at tip, or without any perceptible hook, the end being merely 

 somewhat curved. 



Pachylla is a heavy form with sombre coloring, obtuse abdomen 

 and broad wings. 



Phlkmipelus is closely allied, but more graceful ; with larger, more 

 pointed abdomen, narrower wings and entirely different genitalia. 



Ampelophaga contains smaller forms w'ith short, slender antennae, 

 much more sinuate primaries and weaker legs. This genus makes a 

 very decided approach to the Smerintkld type of structure. 



Thiee of the genera, — Pachylla, Philampelus and Argeus are rather 

 closely allied, the differences being principally comparative. They 

 are recognizable by somewhat different habitus as well as by the 

 differences heretofore pointed out. 



Pachylia seems better marked than Argeus, but of the latter I have 

 had no % for dissection. 



In tabular form, the scheme outlined above, would be as follows: 



Abdomen with a fan-like tuft at tip. 



Primaries not angulated • ^EIlopos. 



Primaries angulated. 



Thorax prominently crested Eliyo. 



Thorax not crested. 



Body not depressed ; head distinct ; abdomen not laterally tufted. 



Ainpliiou. 

 Body heavy, depressed ; head retracted ; abdomen with a series of trun. 



cated lateral tufts Thyreiis. 



Body slender; head retracted, with a distinct frontal crest; vestiture thin. 



Deidaniia. 

 Abdomen not tufted. 



Autennse gradually thickened to tip, not clubbed. 



Autei-ior tarsi with first joint armed with stout spines outwardly. 



Deilepliila. 

 Autennse slender, a small recurved hook at tiii. 

 Anterior tarsi unarmed. 



Abdomen elongate, slender; wings narrow, pointed, graceful. 



Clioerocaiiipa. 



Abdomen shorter, wings broader, anal angle well marked; antenna; with 



longer hook at tip : head large, prominent Argeus. 



