THORELL ON ARANE.E OF COLORADO. 493 



Labrador, but the armature of the tibiiie of the second pair is different in 

 this latter species, which has only 2. 1. spines on the underside of these 

 tibife. 



Gen. Prosthesoia L. Koch, 1872. 



12. P. melancholica n. 



Black, with the palpi and legs dusky yellowish at the base and the 

 tarsi and anterior metatarsi rusty-brown; eyes of the hind row of equal 

 size, much smaller than the fore laterals, which are more than double as 

 large as the fore centrals ; the interval between these latter eyes larger 

 than that between the hind centrals ; legs of the fourth pair much longer 

 than those of the first ; the 4 anterior tibiie destitute of spines ; vulva form- 

 ing a large pale area, which shows two fine brown costfe curved inward 

 and united in the form of a -— v^ behind, and inclosing an area broader 

 than long, scarcely narrowing forward. — 9 ad. Length about 7^ millim. 



Female. — Cephalothorax a little longer than tibia + patella of the fourth 

 pair, rather strongly rounded in the sides behind, then equally narrow- 

 ing forward, with the breadth of the clypeus nearly equaling half the 

 breadth of the pars thoracica ; it is surrounded by a fine elevated margin, 

 rather strongly convex transversely, very finely coriaceous, strewed with 

 hairs, and has a distinct short middle furrow ; the cephalic impressions 

 and three radiating furrows on each side are very faint. The front row 

 of eyes, is rather strongly curved downward, the hind row is straight, the 

 interval between the hind lateral and central eyes is somewhat greater 

 than that between the two hind centrals, which is a little smaller than that 

 between the fore centrals; this latter interval is fully as great as the diam- 

 eter of the central eyes and greater than the interval between these and 

 the fore laterals. The central eyes occupy an area longer than broad be- 

 hind and slightly broader behind than in front ; the hind central eyes 

 are little if at all larger than the hind laterals; the interval between 

 the fore and hind central eyes is double as great as the diameter of the 

 former, and a little greater than the interval between the fore and hind 

 laterals; the fore lateral eyes are oblong, much larger than the other 

 eyes, more than double as large as the fore centrals, which are the 

 smallest of the eight. The mandibles are rather strongly convex 

 toward the base, about as long as the patellte of the first pair, more 

 than double as long as broad at the base, not thicker than the tibiae of 

 the first pair, striated transversely, with hairs and bristles of the or- 

 dinary form. The maxillce are rounded (not sinuated) and curved in- 

 ward in front of the insertion of the iialpi, truncated at the apex in- 

 ward ; they have a stong transverse depression somewhat in front of 

 the middle. The palpi and legs are of the form common in this genus, 

 the tibiie of the first pair incrassated ; the fourth pair of legs are much 

 (nearly with the length of their metatarsus) longer than the first, which 

 are but little longer than the second ; these are nearly with the length 



