TERTIABY DECAPOD CRUSTACEANS. 163 



other genera are distinctively American, viz, Petrochirus, Panopeus 

 (rarely eastern Atlantic), and Mesorhoea. Otherwise the West Indian 

 fossil decapods have a strong affinity with the present Indo-Pacific 

 fauna, as evidenced by Ranina, Scylla (both Recent Indo-Pacific 

 genera but fossil in Europe), Podophthalmus (wholly Indo-Pacific), and 

 Lyreidus (typically and chiefly Indo-Pacific, partly western Atlantic, 

 and fossil in Europe). Moreover, Portunus gdbbi, described below, is 

 related to recent Indo-Pacific species more than to those now living in 

 the West Indies. 



DESCRIPTION OF THE MATERIAL. 



Order DECAPODA. 



Suborder NATANTIA. 



Tribe CARIDES. 



Superfamily CRAGONOIDA. 



Family CRAGONEDjE. 



Genus and species indeterminable. 



(Plate 9, Figure 3.) 



Material. — The telson of a single specimen, from the Yaqui Valley 

 at Cercado de Mao (Bluff 3), Santo Domingo; lower Miocene; C. J. 

 Maury, collector; 1916. 



The following is a description. of this specimen: 



Telson high, narrow, horizontal; tapering for its proximal half, then the 

 sides parallel, tip broken off. On either side a deep groove running the 

 whole length; above, three ridges separated for the basal third by two deep 

 grooves; not far from the base a fine groove begins on the median ridge and 

 is continued nearly to the tip; it divides this ridge in two, each half further 

 on uniting with the submedian ridge of its side; on the outer side of each 

 submedian ridge near its base there is a short ridge, partly visible in dorsal view. 

 Below, the telson is broadly and deeply concave, the concavity narrowing 

 along the middle. All the ridges are smoothly rounded. 



Relationship. — This specimen is not referable to any known genus, 

 as, while the general appearance is that of a cragonid, the grooves of 

 the telson are much deeper than in any of the living forms. 



Suborder REPTANTIA. 



Tribe PALINURA. 



Superfamily ERYONIDEA. 



Family ERYOMD.X. 



Genus and species indeterminable. 



(Plate 9, Figure 4.) 



Material. — A fragment, representing seemingly the greater part of 

 the ischium of the right cheliped of the first pair, from the Yaqui 

 Valley at Cercado de Mao (Bluff 3), Santo Domingo; lower Miocene; 

 C. J. Maury, collector; 1916. 



