1890.] NATURAL SCIENCES OF PHILADELPHIA. 421 



Lycosa. The three are certainly very closely allied. Trochosa, 

 however, with its low, rounded cephalothorax, seems sufficiently 

 distinct ; but Tarentula, at least as far as our one species, T. kochii, 

 is concerned, does not seem to me distinct from Lycosa. 



The genera which occur in our fauna can be distinguished by 

 the following key. I have included Aulonia, as A. aurantiaca has 

 been found both north and south of Pennsylvania, though I have 

 not been able to find it here. 



Family LYCOSIDAE. 



/. Eyes in three horizontal rows. 



a. Upper spinnerets not longer than the lower. 



h. Length of dorsal eye-area more than one-quarter of the 



length of the cephalothorax. Spiders small. Pardosa. 

 hh. Length of the dorsal eye-area less than a quarter of the 

 length of the cephalothorax. Spiders large, or of medium 

 size. 

 c. Head low in front, and sloping obliquely on the sides. 

 ♦ Trochosa. 



cc. Head high in front ; sides more nearly perpendicular. 



Lycosa. 

 aa. Upper spinnerets longer than the lower. 



b. Dorsal eye-area very large, occupying fully one-third of 



the top of the cephalothorax. Aulonia. 



hh. Dorsal eye-area occupying much less than a third of the 

 cephalothorax. Pirata. 



//. Eyes apparently in two horizontal rows, which are convex 

 anteriorly (i. e., posterior eyes so far forward as to be nearly on a 

 line w'ith those of the middle row.) 



a. Front row of eyes equidistant from the second row and the 



anterior edge of the cephalothorax. Ocyale. 



aa. Front row of eyes much nearer to the second row than to 



the anterior edge of the cephalothorax, Dolomedes. 



Genus LYCOSA. 



The spiders of this genus are usually large, with well-developed 

 jaws and strong legs. The front row of eyes is straight, or slightly 

 curved upwards in the middle ; the central pair are somewhat larger 

 than the others. The eves of the second row are the largest, and 



