174 Illinois State Lahoratory of Natural History. 



Chkysendeton. 



The moths of this genus and of Cataclysta are of 

 similar appearance, having rather narrow wings, the 

 hind wings with a series of small patches of metallic 

 scales surrounded by a black background, near the 

 posterior margin. Ocelli are wanting in Cataclysta, 

 present in (Jhr^'sendeton. The immature stages are in 

 all probability much alike, and the larvae aquatic. 

 Cataclysta has not been taken by us in Illinois. 



C. claudialis Walk, {medicinalis Gr.). 



This graceful moth appeared at the electric light in 

 Champaign June 21. Grote's types were from Illinois. 



Hydrocampa. 



The moths of the three genera Hydrocampa, Oligostigma, 

 and Paraponyx show but slight structural differences; 

 the latter has however been usually maintained as 

 distinct because of its remarkable larval structure, the 

 larva of Oligostigma being hitherto unknown. In 

 iSmith's Check List, on. the other hand, Prof. Fernald, 

 doubtless appreciating the undesirability of separating 

 these genera by means of the immature stages, at least 

 so long as our knowledge of them remained so glaringly 

 incomplete, has placed all the North American species 

 of these three genera under Hydrocampa, together with 

 some which had previously been included under Homo- 

 physa, among them H. ohliteralis. Our studies show 

 that two very distinct t^-pes of larvae are thus included: 

 one represented by the species previously assigned to 

 Homophysaand Hydrocampa; the other, by those assigned 

 to Oligostigma and Paraponyx. The general appear- 

 ance of the adults would seem to confirm this group- 

 ing. There seems to be a clear generic distinction pres- 

 ent in the immature stages,— not only in the develop- 

 ment of respiratory filaments, but also in the structure 

 of the posterior feet of the larva and the spiracles of 

 the pupa,— though perhaps not manifest in the imago. 



