378 
Wisconsin Academy of Sciences, Arts and Letters. 
18 
19 
20 
Eye-region wider in front than behind. Spines under tib. 
I 3-3. Male with tibia of palpus longer than tarsus. 
Epigynum with two large contiguous nearly circular 
cavities, in the inner basal part of each of which is a 
rounded elevation. Arizona, New York . Sidusa 
Three anterior and three posterior lateral spines on tibiae 
and two anterior and two posterior laterals on meta¬ 
tarsi of first and second legs, besides 3-3 on tibiae and 
2-2 on metatarsi below . 19 
No such development of lateral spines . 20 
Sternum long, truncated. Male with first three legs, es¬ 
pecially third, heavily fringed. Abdomen with bright 
red spot. Tibial apophysis of palpus long, slender, 
half as long as tarsus. Corythalia 
Sternum nearly round, truncated. Male with first and sec¬ 
ond legs, especially second, heavily fringed. Abdomen 
yellow. Tibial apophysis of male palpus rather stout, 
less than one-third of tarsus . Escambia 
Eye-region wider in front than behind, and fourth leg 
longer than third. Body dark colored wth three 
longitudinal light bands from eyes to end of abdomen. 
Length 9-12 mm. Plexippus Paykullii 
I Spiders without the above characteristics, or with these 
l characteristics differently combined . 
21 
f Spiders large and hairy, at least 8 mm. Cephalothorax 
I heavy, low and flat; eye-region occupying but little 
| more than 1-3 of cephalothorax and equally wide in 
21 -| front and behind; sternum much longer than wide, 
narrowed in front . Marpissa 
Spiders without the above characteristics, or with these 
characteristics differently combined . 22 
Cephalothorax high, heavy and convex; eye-region wider 
behind than in front; eyes small in relation to size of 
spiders; large species, rarely under 7 mm. First legs 
heavy and very hairy, often fringed; falces often 
22 -{ iridescent; often with a group of stout bristles near 
lateral eyes. First and fourth legs longer than sec¬ 
ond and third . 23 
Cephalothorax not heavy; first leg not especially hairy; 
size rarely over 6 mm. 24 
Cephalothorax widest in eye-region or just behind dorsal 
23 eyes . Parnsenus 
Cephalothorax widest in middle of thoracic part_Phidippus 
f Third leg as long as or longer than the fourth (includes 
24 I Marchena minuta <j>, Pellenes, Stoides auratus 
| Talavera and Habrocestum morosum) . 25 
l Fourth leg longer than third. 
2 % > Eye-region wider in front than behind 
Eye-region parallel or wider behind ... 
28 
26 
27 
] Length 5-6 mm. Cephalic parit plainly shorter than 
l thoracic . Habrocestum morosum 
Minute spiders about 2 mm. long. Cephalic part nearly 
20 j as long as thoracic ....Talavera 
