TULLGREN, AR ANE/E FR. THE GRAN CHACO. 5 



To determine tlie systematical position of this genus is 

 a very difficult thing not having a greater material for com- 

 parison. The presence of scopuliform tufts on the anterior 

 tarsi advertises that it does not belong to the Ctenizidae. The 

 absence of the inferior claw seems to me to be of smaller 

 importance. Through the short and robust mamillse and the 

 rastellum it agrees not only with the Ctenizidse but with the 

 groups Cyrtaucheniese and Nemesiese. With these latter it 

 agrees moreover throagh the diagram of eyes, the shape of 

 the cephalothorax, especially the cephalic part, and through 

 the arrangement of the sigillae. 



D. oniatus n. sp. (Pl. 1, fig. 1 a — d). 



Female. — Cephalothorax yellow-brown a little lighter on 

 the thoracic part; longer than broad, very little tapering to- 

 wards the truncated front. Tlie cephalic part strongly con- 

 vex and occupying över half the length of cephalothorax. 

 Central fovea deep, very little procurved. Cephalic and tho- 

 racic impressions well marked. 



Eyes situated on a comparatively high convex and black- 

 coloured ocular tumulus nearly twice as broad as long. Cen- 

 tral anterior eyes very large, circular, about a diameter apart 

 and about twice the diameter from margin of clypeus. The 

 distance from the lateral ones about half a radius. Anterior 

 laterals reniform, tbeir axes longer than diameter of anterior 

 centrals. Posterior laterals ellipsoid, their axes equal to half 

 the axes of anterior laterals and one quarter their axes from 

 these. Posterior centrals very small, ellipsoidal, their axes 

 about equal to half the diameter of anterior centrals, nearly 

 contiguous with the posterior laterals, almost two diameters 

 of anterior centrals apart. 



Cheliceres yellowish brown, scarcely as long as the ce- 

 phaUc area. The rastellum consisting of numerous short 

 black spines. Fang-groove (fig. 1 b) armed on inner side 

 with a series of 7 stout conical teeth; outer margin fringed 

 with thickly-set rufous hairs and floor studded with an 

 irregular row of small cusps, diminishing in size towards 

 the base. 



Labiuyn light brown, broader than long, slightly convex, 

 not studded with cusps. 



