TERTIARY DECAPOD CRUSTACEANS. 177 



The width across front and orbits is about two-fifths of the entire width of 

 the carapace. The orbit is narrow, about one-third as wide as the front and 

 is probably subcircular. Only the upper margin of the left orbit remains and 

 its characters are obscured by cracks in the carapace. Edge of front lacking. 



Of the various species of Zanthopsis described, this one most resem- 

 bles Z. leachii (Desmarest), 1 which also is very uneven. The nodules, 

 however, are very differently disposed in the two forms. The marginal 

 tubercles are antero-lateral in leachii and postero-lateral in bartoh- 

 mceensis. 



Genus PILUMNTJS Leach, 1815. 



Pilumnus subequus, new species. 



(Plate 9, Figure 9.) 



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

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



Material. — Dactylus of right and major cheliped. Cat. No. 324484, 

 U. S. N. M. 



The following is a description of this species: 



A dactylus of small size, dark-colored, stout, strongly curved, with about 

 5 lines of punctae, and above at the proximal end 4 granules. Prehensile teeth 

 few (4 large and 1 small), shallow, subtriangular. A common type of dactylus 

 among the numerous recent species of Pilumnus; the basal granules or spinules 

 are, however, usually more numerous. 



ARCEL&OPILUMNUS, new genus. 



The following is a description of this genus: 



Near Pilumnus. 2 Carapace subquadrilateral, the penultimate tooth of the 

 side margins most prominent; surface rough and deeply sculptured, posteriorly 

 as well as anteriorly. Front bilobed, lobes concave, their outer angle pro- 

 duced but not dentiform. Orbit and basal antennal segment as in PUumnus. 

 Chelipeds stout, rough, unequal; fingers elongate, deflexed. 



This genus is distinguished from Pilumnus chiefly by the fingers, 

 which are long instead of short and stout; by the posterior part of the 

 carapace being deeply sculptured, which is usually not the case in 

 Pilumnus; and by the outer angle of the front not being separated from 

 the remainder of the front. 



Archaeopilumnus caelatus, new species. 

 (Plate 6, Figures 6 and 7; Plate 7, Figures 10 to 13; Plate 8, Figures 4 to 7.) 



Type locality. — Lower half of the valley of the Yaqui del Norte 

 River, in the northern part of Santo Domingo, Haiti; probably lower 

 Miocene; W. M. Gabb, collector. 



Hohtype. — Male. Cat. No. 2261, Mus. Phila. Acad. Nat. Sci. 



'Compare fig. 1, plate 1, of Bell's Monograph of the Fossil Malacostracous Crustacea of Great 



Britain, part 1, 1857. 

 'Leaph, Trans. Linn. Soo. London, vol. 11, pp. 309 and 321, 1815. Type, P. AirteHu* (Linnasus, 



1761). 



