290 bulletin: museum of comparative zoology. 



Labium a little longer than wide (17:16); notches one fourth the 

 total length; sides convex, converging distad; distal margin widely 

 weakly incurved. 



Scopulae of tarsi as usual, those of the anterior tarsi entire though 

 not dense, those of the posterior pairs more sparse and divided by a 

 wide setose band. Tibia I with the usual three pairs of ventral spines; 

 tibia II with the usual distal pair of spines but with single median 

 and basal spines toward caudal side, in place of the usual pairs. No 

 median dorsal spine at base of posterior tibiae, this as usual represented 

 merely by a long bristle in each case. Patellae not armed in median 

 dorsal line. 



Female. Length, 10 mm. Length of cephalothorax, 4 mm.; width, 

 3.1 mm. 



fern. tib.+pat. met. tar. total 



Length of male, 8 mm.; length of cephalothorax, 3.8 mm., width, 

 2.7 mm. 



Localities. — Cuzco, 11,500 feet, July. (Type, M. C. Z. 291, female; 

 para types, M. C. Z. 292, numerous females). Arequipa, 7,600 feet, 

 June 28. (M. C. Z. 323, one female). Urubamba, 9,500 feet, July. 

 (M. C. Z. 293, on male, two females). 



Orinocosa,^ gen. nov. 



Cephalothorax much as in Lycosa, but with sides of head steeper. 



Anterior eyes small, the medians larger than the laterals to which 

 they are closer than to each other; anterior row much shorter than 

 the second, strongly procurved. Eyes of second row large, less than 

 their diameter apart. Quadrangle of posterior eyes wider behind 

 than in front (in type species the length of quadrangle is to length of 

 cephalothorax as 1:3.6 or 3.7). 



Clypeus receding from median eyes; narrow, but equal in width 

 to diameter of an anterior median eye. 



' Greek 'optivos, mountaineer, Lycosa. 



