TERTIARY DECAPOD CRUSTACEANS. 173 



Paratopes. — (a) A male taken at the type locality, much larger than the 

 holotype. It lacks chelipeds. The lateral teeth of the carapace are narrower 

 than in the smaller specimen, their sides somewhat concave. A curved 

 transverse line of granules is seen on the branchial regions leading toward the 

 lateral spine. Enough of the abdomen is exposed to show the sex and generic 

 relation. Cat. No. 2566, Mus. Phila. Acad. Nat. Sci. 



(b) A right chela, also from the type locality; the fixed finger is broken off 

 not far from the base, the dactylus near its middle. Resembles in shape the 

 chela of the holotype, but is much larger, having a maximum height of 32 mm. 

 No other difference is apparent, excepting the slightly greater height of the 

 middle intercostal space of the outer surface. The lobe at the distal end of 

 this space is broken off. Cat. No. 2254, Mus. Phila. Acad. Nat. Sci. 



Additional material. — A dactylus of left cheliped, from the Yaqui 

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

 C. J. Maury, collector; 1916. This finger is of much smaller size (about 

 16 mm. long) than those of the holotype and paratype (6); its grooves 

 are more strongly marked, the deepest grooves being one on the upper 

 half of the outer surface and one on the lower half of the inner surface; 

 a short, shallow groove is at the proximal end of the lower half of the 

 outer surface. (See plate 3, figs. 6 and 7.) 



Relationships. — Although the genus Portunus ( = Neptunus of 

 authors) is represented in the West Indian region by several Recent 

 species of moderate size, our Tertiary species suggests none of them, 

 but is allied to the large Indo-Pacific species. It resembles especially 

 P. pelagicus 1 in the configuration of the carapace and the shape 

 of the female chela and abdomen; it differs from pelagicus in lacking 

 the posterior of the transverse granulate gastric ridges, in the chela 

 not being quite so deep at the base of the fixed finger, and in the sixth 

 segment of the abdomen in both sexes having less rapidly convergent 

 sides. The abdomen of the male in gabbi is nearest that of P. trituber- 

 culatus, 2 the sides of the coalesced (third to fifth) segment being even 

 less convergent than in that species. 



While the fossil species, owing to its wide male abdomen and feeble 

 dorsal ridges, is a true Portunus, it has some features which link it 

 with the genus Callinectes; e. g., the four median frontal teeth are 

 related to those of C. bocourti? in bocourti the outer frontal teeth are 

 larger than the inner, and are about as advanced or even more so; 

 while in gabbi the inner teeth are larger and more advanced. The 

 lateral teeth also resemble those of bocourti much more than they do 

 any of the Portunus species. 



Portunus tenuis, new species. 

 (Plate 7, Figure 7.) 



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

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



« Cancer pelagicus Liniueus, Syst. Nat., ed. 10, vol. 1, p. 626, 1758. 



* Neptunus trituberculatus Miers, Ann. Mag. Nat. Hist., ser. 4, vol. 17, p. 221. 1876. 



» A. Milne-Edwards, Crust. Reg. Mex., p. 226, 1879. 



