WATERLIME GROUP. 41 fl- 



are very thick and strong, and the joints comparatively short, having 

 their origin at about the anterior third of the carapace. Postoral plate 

 lyrate, with the anterior cordiform. Maxillary plates rhomboidal, more 

 than one-half longer than wide ; the inner anterior extremities ex- 

 tending beyond the postoral plate, and distinctly serrate. Second joint 

 strong and wide ; third joint very short ; fourth joint about twice as 

 long as wide ; fifth and sixth joints nearly one-fourth longer than wide ; 

 seventh and eighth comparatively short, as wide as long ; the fixed 

 chela very small. The terminal palette is excessively large, ovate, 

 longer than the preceding joint, and nearly as wide. The thoracic 

 appendage is articulated to the first thoracic articulation in the usual 

 manner : the lower margin of the first joint adjacent to this organ is 

 prolonged in triangular extensions over the next joint ; the appendage 

 itself extends to the fifth joint of the body, and is imperfect at the 

 extremity. 

 Crust very thin. No scale-like markings have been observed, nor rows of 

 scale-like pustules along the dorsal side. 



The simple chelate appendages or spines of the anterior feet are re- 

 markably thick and strong, and were apparently more numerous than in 

 the other species. The extensions or anterior edges of the last joints of 

 the swimming feet are very strongly serrate. 



This species is distinguished by its robust elongate body, the long straight-sided 

 carapace, very anterior eyes, strong and thick-jointed anterior feet, and extremely 

 long swimming feet, with the great development of the terminal palette, and the 

 little dilatation of the two preceding joints. The form of the postoral plate is very 

 remarkable, though its posterior termination is unknown : the appendage is more 

 prolonged and of a different form, and the adjacent articulation is very peculiar; 

 and there are distinctive features in the maxillary plates. 



A single specimen only has been seen. 



Plate lxxxiii, fig. 1. The dorsal side of the specimen, preserving ten joints and a part 

 of the eleventh joint of the body. 



Plate lxxxiii a, fig. 1. The ventral side of the specimen as it lies on the surface of the 

 stone. 



Geological position and locality. In the Waterlime group near Buffalo. 



