152 ENTOMOLOGICAL SOCIETY 



through meadows and rocky cliffs, gives a beneficial influence 

 to a large part of the territory of the District for the subsist 

 ence of the many and varied elements of its Spider-fauna. 



Water, either stagnant or flowing, always exerts a great 

 influence upon the existence and prolific livelihood of the 

 Spider-fauna of a region, as such a condition secures and 

 promotes an abundant supply of insects, which serve as food 

 for Spiders. 



The surface of our territory is undulating and in some parts 

 rather broken. Many of the elevations ,are covered with 

 dense woods of various kinds ; and these, with the verdant 

 meadows and the barren hills in their varied alterations, offer 

 a most suitable abode for the many forms of Arachnida. 



Of course we cannot expect to meet representatives of all 

 the seven orders of this class in the territory of the District ; 

 such forms as the Galeodes, the Pedipalpi and the Scorpions are 

 by climatic reasons excluded from our locality, while the 

 orders Aranece, Opiliones, Chelonethi and Acari are here well 

 represented. It may, however, be proved in future that the 

 Scorpion is also an inhabitant of the District of Columbia, as 

 one species of this order, the Centrums vittatus Say has been 

 found near Fortress Monroe, Va., in Talbot county, Mary 

 land, and in one instance in Baltimore county, and it seems 

 to me quite possible that we may also meet with it here, as it 

 prefers in this latitude the half loose bark of the Southern 

 L,ong-leafed Pine (Pinus tcedd] as a habitation. 



The result of my collecting of A ranees in the District for 

 the last twelve years is as follows : 



The total number of species collected in the limits of the 

 District of Columbia is 370, of which 62 are new and unde- 

 scribed ; the remaining 308 have been described and recorded 

 as coming also from other parts of the United States. 



