390 NORTH AMERICAN INDEX FOSSILS. 



carapace divided by shallow, broad, obtusely subangular cervical 

 sulcus at about one third the distance from the front; lateral 

 ridges more spinose in front of this groove, and sharp, but median 

 one becomes obsolete, and replaced by an ovate-lanceolate or pear- 

 shaped area, elevated anteriorly, and margined by tubercles ; sur- 

 face of carapace minutely granulose. 

 Nanaimo group of Vancouver, B. C. 



32. L. canadensis Whiteaves. Cretacic. 

 More prismatic in form than the preceding species, median ridge 



of post-abdomen sharp, with rounded tubercles; marginal ridges 

 also tuberculate. 



Nanaimo group of Vancouver; Benton of Alberta; Niobrara 

 of Dakota. 



XIX. Callianassa Leach. 



Abdomen much elongated; cephalothorax small, compressed; 

 first, second and last thoracic legs chelate, the first pair the largest ; 

 chelae smooth or with serrated margins; carpopodite joined to the 

 propodite by a straight suture ; nearly of the same shape and width 

 as the latter, but shorter and somewhat contracted behind ; remain- 

 ing joints much smaller; entire body except the outer leg joints 

 soft-skinned, and hence the latter alone are commonly preserved. 

 Readily distinguished by the similarity of the carpopodite and 

 propodite. Jurassic-Recent. 



33. C. whiteavesi Woodward. Cretacic. 

 Fixed finger of propodite rudimentary and stout, only half as 



long as the movable finger (dactylopodite), which is straighter than 

 in other species. 



Pierre-Fox Hills of Assiniboia, and Nanaimo of Vancouver 

 Island, B. C. 



34. C. conradi Pilsbry. (Fig. 1693, a-c.) Cretacic. 

 Claws shorter and broader than in C. mortoni and more evenly 



convex on the two sides, posterior margin of outer side and keel 

 along upper edge not abruptly deflected behind; fixed finger of 

 propodite without the median tooth on grasping face, found in 

 C. mortoni. 



Ripleyan of New Jersey (Tinton beds). 



