MAY FLIES AND MIDGES OF NEW YORK 63 



NORTH AMERICAN HYDROPTILIDAE 



BY KENNETH J. MORTON, F. E. S. (LONDON) 



Some time ago Professor Betten sent to me several tubes con- 

 taining a large number of examples of Hydroptilidae 

 collected at Ithaca, N. Y. The examination of these has re- 

 vealed quite an unexpected wealth of species, so many indeed 

 that they should form a very satisfactory basis from which to 

 start on the investigation of the North American forms com- 

 prised in this wonderful family. With the approval of Profes- 

 sor Needham and Professor Betten, I have here undertaken the 

 attempt to describe the species found at Ithaca, and further ad- 

 ditional material has been received from Illinois (Needham) and 

 from New Mexico (Cockerel!). A few specimens from the col- 

 lection of the late lamented Mr. R. MeLachlan, London, have also 

 passed through my hands. 



The condition of the material, preserved as it is in alcohol, 

 puts a limitation on the character of the descriptions. The ex- 

 ternal fades of the perfect insects is practically lost, most of the 

 hairy clothing having been rubbed off. To a great extent, there- 

 fore, the descriptions will be confined to the details of the $ 

 genitalia, and even with regard to these I may add that much 

 better preparations could have been made from dried specimens. 

 After all the external fades affords very little aid in the determi- 

 nation of the species, although in collecting these insects in a 

 restricted area one learns to know them by their appearance. 

 In the meantime only the males are dealt with. The difficulty 

 of associating with the respective males the true females of say 

 six species of Hydroptila found in the same tube is one 

 that w r ill appeal to any one who ha ever made the attempt. 

 Eaton's memoir on the family (Trans. Ent. Soc. Lon., 1873, 

 pp.125-150) was the first which dealt with these minute insect 

 forms after the newer methods. McLachlan in his Monographic 

 Revision and Synopsis of the Triehoptera of the European Fauna 

 (London 1874-1880) gives a full general account of the family and 

 good descriptions of the European species which were then 

 known to him. As the .best general account existing, McLach- 

 lan's work forms the basis for the present paper as regards 



