180 TERTIARY INSECTS OF NORTH AMERICA. 



HYDROPSYCHE ? OPERTA. 



PL 5, Figs. 52, 53. 

 Phryganea operta Scudd., Ball. U. S. Geol. Geogr. Surv. Terr., Ill, 762 (1877). 



A single well preserved specimen with its reverse; the wings are 

 doubled beneath the body, and unfortunately are overlaid by the larva skin 

 of a dipterous insect, obliterating all the important parts of the neuration. 

 On this account it is impossible to determine it with any certainty, but it 

 can not be referred to the Phryganidse proper, from its slender antenna? and 

 long and slender legs. Renewed study of the specimen since the above was 

 published in the Bulletin leads me to believe that it is one of the Hydropsy- 

 chidae and probably not far removed from Polycentropus, but the vena- 

 tion is too obscure to enable one to speak confidently. The first fork, how- 

 ever, appears to be brief and upcurved, exactly as in Polycentropus and not 

 as given in the plate. The head is detached from the body, and faint traces 

 of the antennae are preserved, but detached ; apparently there are two pairs 

 of spurs to what appear to be the middle tibiae, and the spines of the under 

 edge of the same tibiae are numerous. The abdomen is very well preserved 

 on a side view. 



Length of body, 8 mm ; (portion of) antennae, 7 mm ; tarsi, 3.5 mm ; wings, 

 10 mm . 



Chagrin Valley, White River, Colorado. W. Denton. 



HYDROPSYCHE MARCENS. 

 PL 15, Fig. 7. 



Only two specimens of this species are known ; it seems to have a some- 

 what peculiar neuration, but its imperfection induces me to place it in the 

 genus Hydropsyche in a general sense. The front wings are very long and 

 slender, largest beyond the middle of the apical half, the apical margin 

 rounded but with a slight acumination. The neuration is incorrectly given 

 in the plate. No cross-veins can be accurately determined, but it seems 

 apparent that the discoidal cell must be of unusual size, and even larger than 

 the median cellule, which, on the other hand, must be rather smaller than 

 usual. The legs and antennae are long and slender. 



Length of body, 9 mm ; of front wings, 9-9.5 mm ; of hind legs, 6 mm . 



Florissant. Two specimens, Nos. 1618, 11205. 



