Palaeozoic Arachmda of North America. 



73 



Kustarachne extincta Melander. 

 Text figs. 37, 38. 

 K. extincta Melander, Jour. Geol., Vol. XI, 1903, p. 182, pi. V, 

 fig. 4 ; pi. VII, fig. 5. 



The type and only specimen is in the \\^alker collection of the Uni- 

 versity of Chicago, No. 9236. Careful cleaning of the specimen 

 showed that the description given by Melander 

 is not correct, and the following description 

 should be substituted. 



Total length 15 mm. Cephalothorax with 

 a slightly recurved posterior edge, rounded 

 in front, 6.0 mm. long, 7.0 mm. wide. Two 

 contiguous, perfectly round eyes on a trans- 

 versely ellipsoidal tubercle a little in front of 

 the middle of the cephalothorax. Pedipalpi 

 (not counting the coxae) four-jointed, chelate. 

 Arrangement of coxae same as in K. tenuipes, 

 but the fused coxae of the pedipalpi with a 

 shghtly angular anterior edge. First and pro- 

 bably all trochanters two-jointed, first joint 

 rectangular, second conical. First leg thin 

 and long other legs missing. 

 Abdomen oval, composed of 

 ten segments with two minute 

 segments behind the tenth rep 

 resenting possibly the first 

 joints of a whip. 



Fig. 37- 

 Figure ^-j.— Kustarachne extincta Mel 

 No. 9236, ventral surface 



holotype, Univ. of Chicago Mus. 

 *> 76 

 Figure 38. — Same, cephalothorax. X ~ 



Found in the Pennsylvanic (Lower Allegheny) of Mazon Creek, 

 Illinois. 



ORDER SOLIFUGAE 



Only the first segment of the thorax fused with the head, the last 

 three segments free. Abdomen composed of ten segments. Cheli- 

 cera chelate. Pedipalpi pediform. Trochanters of legs two-jointed. 

 Patella absent. Coxa and trochanter of fourth leg with a row of 

 malleoli on underside. Organs of respiration in form of tracheal 

 tubes. First pair of stigmata behind the coxae of the second pair 

 of legs, second pair on the second abdominal segment, third pair on 



