1908.] NATURAL SCIENCES OF PHILADELrHIA, 173 



8. Epigynal area wider than long, 9. 



Not so, 10. 



9. Distinct lateral ridges enclosing posterior portion of guide both at 



sides and also behind except for short median space between 



ends of ridges (PI. XV, fig. 8), distincta Bl. 



No enclosing ridges at sides or behind, guide extending com- 

 pletely over margins of plate of epigynum posteriorly (PL XIV, 

 fig. 5), californica (Keys.). 



10. Over anterior and median portion of epigynum a narrow and very 



shallow fossa passing behind into a large transversely elliptical 

 depression which is completely occupied by the expanded 

 guide, the lateral ends of which lie in excavations in the side 



ridges (PI. XV, fig. 5), mackenziana (Keys.). 



Not so, 11. 



11. Transverse arms of guide narrowest mesally, widening toward 



their outer ends (PI. XIV, fig. 7), . . . . lapidicina Em, 

 Not so, 12. 



12. Lateral plates extending along guide for much of total length of 



epigynum, gradually narrowing in width anteriorly, . . . 13. 

 Not so, the lateral plates mostly confined to transverse arms, 

 abruptly narrowing and extending forward but a short dis- 

 tance on septal piece, 15. 



13. Guide becoming very narrow toward its anterior end; outer 



margin of epigynum presenting a small abrupt shoulder on eacli 

 side just below middle (PI. XIII, fig. 9), . . pauxilla Mtg. 

 Guide of moderate width at its anterior end, being much wider 

 than the fossa at each side; outer margin of epigynum present- 

 ing no shoulder below middle (PI. XIII, fig. 7), banksi Chamb. 



15. Posterior fovea? clearly wider than long; septum of guide very 



narrow over middle region, at front end strongly expanding in 

 fan-like form; front margin of anterior depression straight and 



moderately wide (PI. XIV, fig. 9), moesta Bks. 



Not so, 16. 



16. Sides of epigynum protruding into an angle in front of middle; 



no distinctly defined lateral ridges in middle region of sides, 

 the sides gradually convexly rounding from middle to outer 

 margin (PI. XIII, " fig. 1), \ . . . . . . saxatilis {B..). 



Sides of epigynum not angulate in front of middle ; more or less 

 distinct lateral ridges along middle region (PI. XIII, fig. 3), 



milvina (H.). 



The key to females above does not include P. longispinata (Tullg.) 

 and labradorensis (Th.)^ of which specimens have not been examined 

 by the author. 



Males. 



1. Scopus short and stout, not at all or but slightly longer than 



broad, 2. 



Scopus several times longer than broad, 7. 



12 



