18 



25| inches, as compared with the known parts of E. scorpionis, 

 which measure 9J inches. Specific characters are hardly exhib- 

 ited bj the specimen and it remains uncertain whether a species 

 of Eusarcus^ larger than E. scorpionis, is to be received as 

 distinct. 



A specimen showing the basal joint of one of the swimming 

 feet (maxilliped or ectognath) of a species of Pterygotus from 

 the same beds is before us, and of which the annexed outline 

 figure has been drawn by Mr. Henry Chandler. 



For the species the nnme of Pterygotus Cwm/mingsi is pro- 

 posed, in honor of the donor. In the specimen the toothed man- 

 dibular margin is well shown with a portion of the adjoining 

 lateral margins on each side, while the outline of the remaining 



