606 NEUROrTERA. 



to rushes or other aquatic plants. The}' are of a cj'lindrical 

 form, terminating at the top in a sudden point ; they are at- 

 tached side by side with the greatest regularity." The larvse, 

 as in those of Corydalus, are broad and flattened, with a pair 

 of long, thick, respiratory filaments attached to the side of 

 each ring of the abdomen. The body of the pupa is curved; 

 with the wings laid along the breast, much as in the Phry- 

 ganeid pupae. The larva is active and predaceous, being 

 armed with strong jaws. When full-fed it leaves the pools or 

 streams in which it has been living and makes an earthern cell 

 in the bank, in which the inactive pupa undergoes its remain- 

 ing transformations. 



In Skdis the prothorax is large and square, almost equal in 

 size to the head ; there are no ocelli ; the antennae are filiform, 

 and the wings iiTegularly net-veined, the veins being stout. 



The fourth joint of the tarsi is 

 dilated and twice lobed. The 

 larva is much like that of Cory- 

 dalus, but differs in having the 

 abdomen terminating in a 

 '^^^' '^^'^^ "long and slender setose tail." 



SkiUs infumata Newman (Fig. 593, caudal appendages of tlu^ 

 male, from Walsh) is black, with the head not narrower be- 

 hind, while S. Americana Rambur is rust-red, and the head is 

 narrower behind. The wings expand about an inch. 



Chauliodes is a much larger insect, with a quadrangular pro- 

 thorax nearlj'^ as large as the head. There are three ocelli 

 placed close together, and the antennae are cither pectinated or . 

 serrated. The wings are veiny, the transverse veins slender. 

 The joints of the tarsi are cylindrical, and the caudal appen- 

 dages of the male are conical and simple. Walsh describes the 

 larva of C. rastricornis Rambur as resembling that of Cory- 

 dalus, but being much smaller, measuring 1.60 of an inch, and 

 the abdomen has one segment less, with no caudal setae, "so 

 that Chauliodes forms a connecting link in this respect between 

 Corydalus and Sialis, the larva of which is said to have 'one 

 long, slender, setose tail,'" and the under side of the abdomen 

 is "entirely destitute of the remarkable paddle-like branchii\3 

 found in Corydalus." The pupa resembles that of Corydalus. 



