116 



Alexander Petrunkauich, 



straight. The tenth tcrgite was probably the last. On the edges of 

 the abdomen are visible the pleurae. They are not segmented, and 

 were probabh' soft. Chelicera very small, turned downward, with a 

 line dividing them half-way into two parts probably representing the 

 fingers of a chela. At the sides of the chelicera are visible the troch- 

 anters of the pedipalpi separating the legs of the first pair. The 



outlines of the coxae of the 

 first pair cannot be traced 

 all the way backward. The 

 coxae of the second pair 

 are triangular and widely 

 separate. The coxae of 

 the third and fourth pair 

 are very long, contiguous, 

 meeting in a median line. 

 All trochanters one-jointed. 

 Trochanter of the first part 

 of legs conical, the others 

 rectangular. The first leg 

 is slender and long, its femur 

 measures 3.85 mm., patella 

 2.66 mm. tibia 7.8 mm., 

 metatarsus 2.7 mm., tarsus 

 missing. Second leg is the 

 shortest ; it is heavy, its 

 femur and patella of the 

 same length, tibia some- 

 what shorter, metatarsus 

 shorter than the width of 

 the patella, tarsus conical 

 The third leg is heavier 

 and longer than the second, 

 but its three distal joints are missing. The fourth leg is still 

 heavier and longer, but only trochanter and part of femur preserved. 

 T.he whole body is smooth. 



The species is of great interest since it combines characters of two 

 orders : Opiliones and Phalangiotarbi. The arrangement of the coxae 

 and the chelate chelicera remind of the former, wliile the segmentation 

 of the abdomen is tj'pical of the latter. 



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

 IlUnois. 



Fig. 70. 



Figure 70. — Heterotarbus ovatus n. sp., holo- 



type, Daniels coll., dorsal surface, with the 



coxae and chelicera superimposed on the 



cephalothorax. X 



