chamberlin: the arachnida. 291 



Upper margin of furrow of chelicera with three teeth of which the 

 median is longest; lower with three teeth of which the most proximal 

 may be reduced. 



Labium as wide as long or nearly so. Basal notch in type short, 

 about one fourth the total length. 



Legs distally slender. Metatarsus IV equal in length to tibia C + 

 patella IV. Tarsi setose beneath, none truly scopulate. Tibia I 

 with three pairs of ventral spines, the distal reduced, the first two but 

 slightly exceeding the diameter of the joint. Tibiae III and IV above 

 with a stout median apical spine and a median basal spine. 



Epigynum with median guide and transverse arms; lateral cavities 

 deeper cephalad as in Lycosa. 



Genotype. — Orinocosa aymara, sp. nov. 



Most readily distinguished from related genera by presence of the 

 stout median dorsal spines on the posterior tibiae. Its affinities seem 

 to be closest with Lycosa. 



Orinocosa aymara, sp. nov. 

 Plate 24, fig. 7-8. 



Carapace with sides nearly black; on each side a narrow, supra- 

 marginal light line which does not reach upon pars cephalica; median 

 pale stripe beginning back of second eyes extending between third 

 behind which it widens to width of eye-area, then abruptly narrower 

 some distance in front of the thoracic furrow and gradually narrowing 

 to caudal margin, the stripe embracing a dark mark back of each eye 

 of the third row. Sternum black, with a median longitudinal yellow 

 mark in the anterior half. Labium dusky. Endites brown or some- 

 what chestnut. Chelicerae light chestnut. Coxae of legs beneath 

 yellow; other joints yellow, with exception of tarsi closely ringed with 

 black, there being three distinct annuli on femora of which the distal 

 is very broad and two on the tibia of such breadth that only a small 

 ring of yellow remains at the middle; metatarsus also with two broad 

 rings nearly embracing the whole length. Venter of abdomen brown, 

 black at base of spinnerets; sides with a few black spots; a large 

 solid black spot over each antero-lateral corner; dorsum greyish yel- 

 low covered with a very fine areolation in dark, embracing a short, 

 faint lanceolate outline at base which sends off a pair of short side 

 branches at tip and one on each side near middle, behind tip of 



