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 
