140 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 18 



The writer did not have an opportunity to examine the types of 

 Faxon's species, but fortunately they were well figured and specimens 

 were available from the type locality which agreed in every particular 

 with the original descriptions. 



The writer wishes to express his appreciation to Captain Allan 

 Hancock for the great privilege of using the collections and facilities of 

 the Foundation; to Dr. John S. Garth for his help and guidance; and 

 to Dr. Waldo L. Schmitt and Dr. Fenner A. Chace for their assistance 

 and for permission to examine the type specimens in the United States 

 National Museum. 



PYLOPAGURUS Milne-Edwards & Bouvier 1893 



Chelipeds dissimilar and unequal, the right much larger, highly 

 developed as a more or less discoidal operculum. Fourth pair of thoracic 

 legs subchelate. External maxillipeds widely separated at base, exopodite 

 of all three pairs flagellate. Abdomen not spirally coiled, straight or 

 merely flexed; paired abdominal appendages present on first somite of 

 female only ; vasa deferentia of male not extruded. 



Genotype: Not designated. The genus was erected by Milne- 

 Edwards and Bouvier to accommodate only forms found in the Carib- 

 bean. Since the writer has not had an opportunity to examine these 

 genosyntypes, the designation of a genotype is not possible in this paper. 



Key to the Eastern Pacific Species of Pylopagurus 



I. Carpus of major cheliped with three or less teeth on inner mar- 

 gin of dorsal surface. 



A. Telson with "V" shaped notch in terminal margin, strong 

 curved teeth at each edge of notch; margins of opercular 

 face of hand a low subserrate ridge. 



1. Major cheliped discoidal, widest portion at level of base 

 of dactyl ; carpus length less than twice its width . . 

 holmesi 



2. Major cheliped spatulate, widest at point distal to base 

 of dactyl; carpus length more than twice its width 

 longicarpus 



B. Telson a simple semioval plate with entire margins; mar- 

 gins of opercular face of large hand with distinct denticula- 

 tions. 



