TERTIARY DECAPOD CRUSTACEANS. 181 



Material— Dactylus of right cheliped, holotype. Cat No 3244S7 

 U. S. N. M. ***»/, 



The following is a description of this species: 



The distal portion of the dactylus is lacking. The proximal end of the upper 

 surface is broad and flat and inclosed by 5 irregular granulated knobs- aides 

 compressed, in the middle slightly concave, and unevenly granulate, granules 

 most numerous on the inner surface. Prehensile teeth very low and flat the 

 proximal tooth more than twice as large as the next one. 



Relationships. —In its general characters resembles the dactylus of 

 the recent P. (Platylambrus) serrata (Milne-Edwards), 1 which has a 

 shorter finger, prominences at proximal end above more spiniform, 

 sides not concave. 



Parthenope, indeterminable species. 

 (Plate 7, Figures 8 and 9.) 



Material. — Dactylus of right cheliped, 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 species: 



Resembles the preceding, but less curved and more slender, sides flat but 

 not concave, outer side more granulate than inner, and having an uneven, 

 longitudinal line of coarse granules not far above the fingers on the proximal 

 half; upper surface flattened along the proximal half, and bordered by stout 

 spines and spinules; one of these spines projects outward above the condyle 

 articulating with the palm on the outer side, and is seen at the top of figure 8 

 at the left-hand end; the condyle is broken off and shows in cross-section; 

 prehensile tubercles 10, the proximal pair confluent; tuberc'es low but better 

 developed than in the preceding species. Upper part of distal end of finger 

 missing. 



Genus MESORHCEA Stimpson, 1871. 



Mesorhcea mauryae, new species. 



(Plate 7, Figures 1 to 4.) 



Type locality.— The Yaqui Valley at Cercado de Mao (Bluff 3), 

 Santo Domingo; lower Miocene; C. J. Maury, collector; 1916. 



Material.— Two specimens, a right manus with propodal finger 

 attached (holotype) and a right manus of smaller size, without fingers 

 but with carpus attached (paratype). Cat. No. 324489, U. S. N. M. 



Measurements.— Length of holotype on outer margin, this being the 

 most complete, 8 mm.; greatest height, measured on inner surface, 

 4 mm. 



The following is a description of this species: 



The holotype has 8 teeth on the upper margin, 13 on the outer and 10 on 

 the inner margin; teeth of outer and inner margins short, those of the outer 

 margin the smallest, those of the inner margin intermediate 111 size. The 

 inner surface widens greatly from the proximal to the distal end, lower surface 



1 Lambrus aerratus Milne-Edwards, Hist. Nat. Crust., vol. 1, p. 357, 1834. 



