Palaeozoic Arachnida of North America. 91 



ascertained. The thoracic part is rather flat, but the cephaHc part 

 elevated, highest at the eye tubercle, gradually sloping laterally and 

 posteriorly to the oval depression. Abdomen flat, oval, 6.0 mm. wide 

 in the middle. The segmentation not as clear as in the type specimen, 

 the lines being rather faint. Chelicera heavy and long. Of the legs 

 and palpi only fragments preserved. 



Specimen No. 163, Peabody Museum. Text fig. 54. 



A badly crushed specimen, probably belonging to this species. 

 Only part of the abdomen, four right and two left legs preserved. 

 The abdomen is oval, six segments can be counted, the lines between 

 the segments quite distinct. First leg almost complete. Femur 

 6.5 mm. long, patella and tibia 9.3 mm., metatarsus 6.5 mm. with a 

 row of seven round depressions. Second leg: tibia alone 6.0 mm., 

 metatarsus 6.03 mm., tarsus 2.8 mm. Both metatarsus and tarsus 

 with a row of round depressions of which the metatarsus has seven 

 and the tarsus four. Third leg : femur 7.3 mm. Fourth leg : femur 

 8.5 mm., patella + tibia 10. o mm., metatarsus 8.0 mm. The tibia 

 of the leg close to the abdomen (probably the fourth left leg) has a 

 row of eight round depressions. 



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

 Illinois. 



Arthrolycosa danielsi n. sp. 

 Plate VIII, figs. 45, 46 ; text figs. 55, 56. 

 The type and only specimen of this species is in the collection of 

 Mr. L. E. Daniels. It is much better preserved than either of the 

 three specimens of the preceding species. Total length, without 

 mandibles, 14.5 mm. Cephalothorax flat, 5.6 mm. long, 5.0 mm. wide 

 in posterior ^/g, oval, with recurved posterior margin. Two small 

 tubercles in the middle of the cephalothorax, and radiating from 

 them four pairs of ridges. The transversely ellipsoidal depression, 

 the mould of the eye tubercle, touching the anterior margin. In it 

 are two pairs of oval depressions, moulds of the eye lenses. Abdomen 

 shows clearly six segments but, as in the preceding species, the true 

 number of abdominal segments was probably greater. Small, round, 

 punctate depressions probably mark the attachment places of the 

 dorso-ventral muscles. The chelicera strong, angular, prismatic with 

 a thickened inner edge. Of the pedipalpi only the coxae and trochan- 

 ters preserved, but it is impossible to say whether the coxae had a 

 maxillary lobe. Legs all in position, but all joints beyond the femur 

 missing. Coxae of first and second pair triangular. Trochanter 



