1 82 AXEL LEONARD MELANDER 



mark on the stone which might have been caused by a terminal 

 seta. This is as fortuitous as in the other species, but its pres- 

 ence casts even darker gloom over the systematic position of 

 the genus. 



Length of body 15"'°, width of cephalothorax 6.5°"°, length 

 of abdomen without the pygidium 9°*™, width of abdomen 7™™, 

 width of first subsegment 2""™, length of second leg (imperfect) 

 24""°, width of second leg beyond body 0.75-0.3""". 



Carboniferous. Mazon creek, Illinois. 



Type. Pal. Coll. No. 9235. 



Although the imperfect type of this genus offers but few 

 salient characters, the present form is placed congeneric with it 

 in entire confidence. It concurs with the characters of no other 

 Anthracomart, but agrees with Kustarach?ie tenidpesm its general 

 form, slender, elongate, but somewhat stouter legs, and similar 

 pygidium. However, it is quite distinct in the sculpture of the 

 abdomen. 



5. Kustarachne exstincta sp. nov. (Plate V, Fig. 4; Plate VII, Fig. 5). 



A single specimen in fragmentary condition. Cephalothorax 

 confused, apparently transversely rounded; the coxae large 

 and meeting about a deep central depression; the post-plate (if 

 there be one) not indicated. Abdomen rounded oval, its seg- 

 mentation rather distinct; seven and possibly eight segments 

 indicated, of which the basal segments are longer than the api- 

 cal, the diminution in size being gradual. The last three seg- 

 ments are outlined by an impressed line. At the termination 

 of the abdomen is a triangular two-jointed pygidium with a 

 prominent mammilliform spinnerett on each side of the last seg- 

 ment. At some distance beyond the body there is an indication 

 of a slender setiform appendage, though whether this is a por- 

 tion of the post-abdomen or a fragment of a tarsus cannot be 

 ascertained. The latter view seems more likely the correct one, 

 and would also explain the "post-abdomen" of the other spe- 

 cies. The lateral sulcus is vague, but seems to be distant from 

 the margin of the abdomen; this may be due to the crushed and 

 contorted condition of the fossil. No median grooves or ridges: 

 surface of the body minutely and densely punctulate, the punc- 



