Natural History of District of Columbia — McAtee 91 



may be found in the writings of Ward ^^ and Coues.*^ 

 Approaching the subject from a somewhat different point of 

 view, only brief descriptions of localities will be given, but 

 an effort will be made to point out distinctive features of 

 various areas, and especially to name the peculiar or at least 

 characteristic species that have been collected in each. 



In the last chapter, where the Magnolia bogs were treated 

 in detail, the prevalence of sandy soils in the Coastal Plain 

 was mentioned. This characteristic is especially noticeable 

 at what have proved to be the most interesting collecting 

 places in the Coastal Plain, one of which is Beltsville. The 

 Powdermill Bogs, as stated in the foregoing chapter, are 

 located about two miles west of Beltsville. They do not 

 monopolize the interesting features of this region, however, 

 as the country in all directions about them has proved to be 

 good collecting ground. Among insects bee-flies (Bomby- 

 liidae) and robber-flies (Asilidae) are especially numerous 

 both in individuals and in species. Here only in the Wash- 

 ington region have been captured Lepidophora, Systoechus, 

 and Metacosmus of the former family, and only here and 

 near Berwyn an undescribed species of Rhabdoselaphus of 

 the same family. Of the Asilidae, Asilus johusoni and Dasyl- 

 lis champlaini have been collected only at Beltsville, and of 

 Tabanidae or horseflies, Tabaniis astutns and T. super ju- 

 mentarius have been obtained only here and T. recedens and 

 Chrysops cucliix here and in the Eastern Branch country 

 towdrd Berwyn. Three species of Syrphidae: Microdon 

 craigheadi, Eristalis saxorum and Xijlota facialis, also have 

 only been taken in the Powdermill vicinity. The bogs are 

 an especially good place to find the Dascyllid beetle, Odon- 

 tonyx trivittis. Interesting species of Elater are attracted 



«« Flora, 1881, pp. 17-26. Avifauna, 1883, pp. 11-27. Less compre- 

 hensive, but nevertheless interesting matter bearing upon this subject was 

 published by Dr. E. L. Greene, in Cybele Columbiana, 1, No. 1, Dec, 1914, 

 pp. 11-14. Dr. Greene's remarks apply chiefly to the Upper Potomac Val- 

 ley. The "localities of special interest to the botanist" of Ward include 

 the Rock Creek Region ; the Upper Potomac Region ; the Lower Potomac 

 Region ; the Terra Cotta Region ; the Reform School Region ; the Holmead 

 Swamp Region, and the Eastern Branch Region. Coues treats the Poto- 

 mac River Region (High Island to Alexandria), the Eastern Branch Re- 

 gion (Bladensburg to Giesboro) and the Rock Creek Region. 



