1904.] NATURAL SCIENCES OF PHILADELPHIA. 261 



DESCRIPTIONS OF NORTH AMERICAN ARANEiE OF THE FAMILIES 

 LYCOSID^ AND PISAURID^:.! 



' BY THOMAS H. MONTGOMERY, JR. 



A very considerable number of species of spiders of the families 

 Lycosidffi and Pisam-ida? have been described from North America, 

 but for the most the descriptions have barely diagnostic worth. At 

 the present time it is practically impossible to identify most of the 

 species of Walckenaer, Blackwall, Hentz and some others, because 

 some of their species are so insufficiently described that a particular 

 description applies equally well to a number of species. By far the 

 most thorough work so far is that of KeyserHng. When the American 

 species are better known than they are at present we shall be in better 

 position to identify the species named by the earlier writers, for then 

 the identification can be done by the process of ehmination. The 

 more deeply one enters into the closely intergrading species of the 

 Lycosidai especially, the more doubtful seems to be the character of 

 attempts to recognize poorly described forms. Nearly the whole 

 southeastern section of the United States and the greater part of the 

 region west of the Mississippi river have been untouched by modern 

 arachnologists; with such a hiatus in the material for comparison, it 

 would be unscientific to make sure of the status of species known only 

 by inadequate diagnoses. It is right to attempt, as far as possible, 

 to recognize the species of earlier writers, but not to uphold names when 

 the type specimens are lost and when the type descriptions are not 

 decisive. When all the species are known, the trial can be undertaken 

 of determining the earlier species. 



The Lycosidffi and Pisauridffi are particularly interesting groups 

 because of the difficulties in the way of their study. Not only do 

 the species intergrade closely, but there is very considerable individual 

 variation apart from geographical variation, and the genera are as 

 difficult to define sharply as are the species. No groups are better 

 adapted to prove the idea that the species, as the higher groups, are but 

 concepts, and their dehmitation necessary purely for purposes of de- 



T^tributions from the Zoological Laboratory of the University of Texas, 

 No. .57. 



