C. E. Beecher — Cambrian Earypterid Remains. 365 



The specimen here described at once suggests the familiar 

 and well-known genus Eurypterus, and only when its charac- 

 ters are studied in connection with its geological occurrence is 

 it apparent that its differences are of sufficient importance to 

 warrant its generic separation. The specimen represents nearly 

 the entire dorsal test of the animal and consists of the 

 cephalothorax with the abdominal segments, including the 

 telson spine. 



The cephalothorax is comparatively shorter and wider than 

 in Euryptents, the eyes are further forward, nearer together, 

 and more oblique, and besides the telson but eleven abdominal 

 somites can be determined on the dorsal side, instead of twelve 

 as in Enrypterus. These differences are considered as indica- 

 tive of a new genus and it is proposed to recognize this type 

 under the name Strabops nov. gen., with Strabops Thacheri 

 n. sp., as the type species. The generic name is in allusion to 

 the inward turning or squinting of the eyes (aTpa/36s squint- 

 ing, and oyjrL? face). 



Doubtless many generic differences will appear when the 

 appendages of this type are obtained. The differences in the 

 characters available for comparison are quite as great as 

 between Euvypterus and Doliefwpterus, Stylonurus, Anthra- 

 conectes, or Eusarciis. This taken with the fact that practi- 

 cally all the Cambrian genera, especially the more highly organ- 

 ized types, became extinct long before the Upper Silurian, 

 lends support to the conclusion that Strabops is generically 

 distinct from any hitherto known form. 



Strabops Thacheei gen. et sp. nov. (Plate VII.) 



Body broadly ovate in general outline exclusive of the tel- 

 son, slightly convex in the specimen, though probably quite 

 arched both transversely and longitudinally in life, as indicated 

 by the outline of the separate segments. 



Cephalothorax short and broad, length less than one-half the 

 width, anterior and lateral margins regularly rounded, posterior 

 margin gently curved in the middle and turning obliquely for- 

 ward toward the genal extremities, which are obtusely angular. 



Eyes medium sized, ovate, narrow ends pointing obliquely 

 inward, situated in the middle of the anterior half of the 

 cephalothorax, distant about the length of one eye, connected 

 anteriorly by a distinct arched line or fold. The eye tubercles 

 are mostly exfoliated, and their convexity and surface cannot 

 be determined. Ocelli indicated by two spots midway be- 

 tween the eyes. 



Abdomen. The dorsal side shows eleven segments exclusive 

 of the telson. The axis in the specimen is slightly convex 



