398 ENTOMOLOGICAL NEWS. [March,. 



one specimen is possessed, or two o's, thus oo, if there are two 

 or more of the same species in the cabinet, and add the neces- 

 sary strokes to complete the male ( $ ) or female ( 9 ) sign 

 when the sex is determined. A list checked off in this manner 

 is particularly useful when studying other collections. 



I hope that a general expression of opinion on this subject 

 will be forthcoming-. 



On the Habits of Tachopteryx Thoreyi. 



(Order Odonata.) 

 BY E. B. WILLIAMSON. 



Tachopteryx Thoreyi Hagen has been taken in Massachusetts, 

 New 7 York, Pennsylvania, Maryland, Kentucky, North Caro- 

 lina, Texas and Florida. Mr. J. L,. Graf first observed the 

 species in Pennsylvania ; and I am indebted to him for the 

 dates indicating the seasonal range of the species in Allegheny 

 County, where he found it. Mr. H. D. Merrick, during the 

 season of 1899, took the species in Beaver and Fayette coun- 

 ties, Pennsylvania. During June of 1899, Mr. Graf and the 

 writer collected a few specimens near Pittsburg, in Allegheny 

 County, in the locality where Mr. Graf had observed the spe- 

 cies the year before. Our collecting ground w T as along Squan 

 Run, a small western affluent of the Allegheny River, a few 

 miles above the Ohio River. The creek has a length of ten or 

 fifteen miles. A mile above its mouth it flows through a level 

 valley, possibly an eighth or a quarter of a mile w y ide. The 

 valley consists of pastured or cultivated fields, wdth some waste 

 patches of willows and elders. The sides of the valley are 

 shaly bluffs or hills, fifty or one hundred feet high, covered with 

 brush, hemlocks and small timber. The stream zigzags across 

 this valley, striking first one side, then the other. It has been 

 a larger stream, and its course has changed from time to time 

 during recent years, leaving occasional pools scattered over the 

 valley. At one place there is a small sw r ampy tract, an acre or 

 two in extent, near the southern side of the valley. Here 

 sedges, the brackenfern, turtle's head and closed gentian grow 7 . 

 In this valley, a mile in length, closed in by its wooded sides 

 and cut by the small stream which wanders through it, 7 lie/top- 



