6 Wisconsin Academy of Sciences, Arts and Letters. 



7. Thoracic part divided by a marked constriction into a shorter an- 



terior and a longer posterior portion; quadrangle of eyes wider 

 than long Synemosyna. 



8. Thoracic part not divided; quadrangle of eyes much longer than 



wide Synageles. 



9. Cephalic part at least as long as thoracic ' 11 



10. Cephalic part shorter than thoracic 31 



11. Cephalic part occupying f of the cephalothorax ^ Homalattus. 



12. Cephalic part occupying plainly less than f of cephalothorax 13 



13. Spiders very small — not so much as 3 mm. long 15 



14. Spiders ^ not very small 17 



15. Quadrangle of eyes equally wide in front aitd behind, legs 4, 3, 1,2 



^ Neon. 



16. Quadrangle of eyes wider behind, legs 4, 1, 2, 3 Ballus. 



17. Quadrangle of eyes equally wide in front and behind; first row 



strongly curved; cephalothorax very convex, with cephalic part 

 strongly inclined forward, and falling steeply behind. . . Agobardus. 



18. Quadrangle of eyes wider behind; first row straight or very 



slightly curved; shape of cephalothorax unlike the above 19 



19. Cephalothorax high, nearly as wide as long; dorsal eyes at widest 



j)oint of cephalothorax, oj)posite a corner, and projecting; quad- 

 drangle of eyes, looked at from above, seeming to occupy f of 

 cephalothorax Zygoballus. 



20. Unlike the above Eris. 



21. Quadrangle of eyes wider in front 23 



22. Quandrangle of eyes wider behind, or equally wide in front and 



behind 27 



23. First row of eyes straight; patella + tibia III shorter than patella 



-f tibia IV ASTIA. 



24. First row of eyes curved; patella + tibia III equal to patella -j- 



tibia IV 25 



25. Dorsal eyes nearer to each other than to lateral borders; legs ( $, ) 



1, 3, 4, 2; (?) 4, 3, 1, 2 ; Prostheclina. 



26. Dorsal eyes further from each other than from lateral borders; 



legs (3 2) 473", iT^ .' 5 s^iTjg_ 



1 The cephalic part extends from the anterior margin of the lateral eyes of the first row 

 to the posterior margin of the eyes of the third row. 



2 The only North American species of this genus yet known has metallic reflections, and 

 when the spider is looked at from above the cephalic part seems to occupy nearly the whole 

 cephalothorax. 



^Zygoballus sexpunctatus H. is only 3 mm. long, but is distinguished from Neon and 

 Ballus by its peculiar falces, as well as by the shape, and greater height of its cephalo- 

 thorax. 



■• In Neon the dorsal eye is plainly larger than the anterior lateral. 



^ In Saitis legs III and IV are much longer than I and II, while in Prostheclina the differ- 

 ence is not so marked. 



