44 



5. Pterygotus, ? sp. (Plate III., Fig. 2.) 



One single carapace has been found, which exhibits the dorsal 

 side. It is a semi-eliptical with a proportion between its length and 

 width of seven to nine; its sides are slightly rounded, and form a 

 regular curve with the front. The eyes are marginal and project 

 beyond the outline of the carapace; they must have been nearly, if 

 not perfectly circular in shape, as their present length is iH inches, 

 and the greatest width almost 1 inch. Their surface resembles very 

 closely the facets of the eyes of insects. The markings on the sur- 

 face of the carapace have all been obliterated excepting those on the 

 anterior and lateral margins, which are covered with small, scale- 

 like processes. 



Length of specimen, 3K inches; greatest width 4K inches. 

 Found in the water-lime group near Buffalo. 



Owing to the fact that the specimen presents no specific marks 

 whatever, and in view of our limited knowledge of the genus, I have 

 not referred it to any species. 



6. Pterygotus macrophthalmus, Hall. ? 



The specimen consists of a perfect carapace with very distinct 

 marginal eyes and outline. It presents the same proportions and 

 also the small, central tubercle of this species (Paleontology of New 

 York, Vol. III., page 418), although this latter is not very distinct, 

 but differs in having a more square-shaped carapace. 



The two swimming-feet which project from under the carapace 

 show the seventh joint with the triangular piece attached by a sol- 

 dered suture along one-half of its width, while from the other half 

 there is a triangular extension of the joint. (B. B. S. N. S., Vol. 

 IV., No. 1.) The palette is ovate. There is no terminal palette. 



7. Pterygotus Buffaloensis, Pohlm. (Plate III., Fig. 3.) 



Another fragment of this species has been found, which illus- 

 trates the "chelate antennae " of the genus. The specimen shows 

 this appendage complete. The free ramus has its teeth standing at 

 right angles to the edge, like P. Cummingsi, Grote & Pitt (B. B. S. 

 N. S., Vol. III., p. 18), and P. cobbi, Hall (Paleontology of New 

 York, Vol. III., 417), but the fixed ramus of this chela has the 

 teeth inclined at an angle of about 45 to the edge, like the one 



