1889.] REV. O. p. CAMBRIDGE ON NEW ARANEIDEA. 45 



Family Theridiid^. 

 Gen. nov. Chasmocephalon. 



Cephalothorax short-oval ; caput large and very convex above ; 

 the ordinary oblique indentations dividing it from the thorax are 

 greatly exaggerated, forming a deep chasm or cleft on each side. 

 The posterior extremity of the thorax is broad and strongly indented 

 or excavated in a curved form, forming a kind of socket into which 

 the pedicle joining it to the abdomen fits. 



Eyes of very unequal size ; in three well separated groups occupjang 

 the whole width of the fore part of the caput ; the anterior pair 

 of the central group smallest, the rest nearly equal. The clypeus 

 considerably exceeds in height half that of the facial space, occupying 

 about, or even more than, two thirds of it. 



Legs slender, moderately long, I, 4, 2, 3 ; furnished with hairs and 

 bristles only. 



The maxillce are short, curved, inclined towards the labium, and 

 somewhat pointed at their extremities on the inner side. 



Labium short, broad, and round at the apex, which reaches nearly 

 to tlie extremities of the maxillae. 



Abdomen considerably elevated in front and projecting greatly 

 over the base of the thorax, with which it is connected by a distinct 

 pedicle, the abdomen having also a kind of socket or excavation to 

 receive it. Besides the usual spiraculur openings there is a long 

 transverse one beneath the abdomen just in front of the spinners. 



Chasmocephalon neglectum, sp. n. (Plate II. fig. 6.) 



Adult male. Length scarcely over half a line. 



The surface oHhe cephalotkorax, which is of a clear bright brownish- 

 red hue, is granulose ; the oblique cephalic indentations are deep 

 and sharply cut, looking as if they would sever the caput from the 

 thorax ; the other normal (thoracic) grooves are also of somewhat 

 the same nature, though very much less strong ; the posterior end 

 of the thorax is broad and deeply excavated ; the hinder part of 

 the caput is well rounded, the fore part flatter. 



The eyes of the central group form a trapezoid whose anterior side 

 is much the shortest ; the pair of eyes composing this side are very 

 minute and contiguous to each other. The posterior pair are oval, 

 large, contiguous, and of a pearly hue, their diameter equalling more 

 than double that of the anterior pair ; each of these is separated 

 from the anterior eye opposite to it by an interval only about equal 

 to the diameter of the latter. The hind lateral eye on each side is 

 separated from the hind central next to it by about U diameters of 

 the former, and each fore lateral eye, which appears to be rather the 

 largest of the eight, is contiguous to its hind lateral eye. The lateral 

 eyes are also pearly, the fore centrals being a little darker. 



The legs are dull orange-yellow ; the hairs longish, but not very 

 numerous, and there are also a few prominent bristles. 



The palpi are unfortunately missing. 



Falces moderately strong, rather long, straight, and a little inchned 



