THE BRACHYURA AND MACRURA OF PORTO RICO. 
7 
Uca mordax (Smith). 
Gelasimus mnrdax Smith, Trans. Conn. Acad. Sci., n,135, pi. it, f.3,pl.iv, f. 4, 4a, 1870. 
Uca mordax Rathbun, Proo. U. S. Nat. Mus., XXII, 276, 1900. 
Front, broad and shallow; width at base or posteriorly about one-third the width between the 
anterior angles of the carapace; anterior margin almost straight. Lateral margin of carapace strongly 
curved inward anteriorly and forming blunt angles. Palm elongate, narrow toward the carpus; the 
oblique ridge on its lower inner surface is usually tuberculate and very much thickened, being several 
tubercles in width. In the Porto Rican specimens these tubercles are almost obsolete except at the 
proximal end of the ridge. The two rows of tubercles at the base of the daetylus on the inner surface 
of the palm are not parallel, but diverge from each other toward the upper margin. 
A large species, over an inch in width. Length of male from Hucares, 16.4 mm. ; width 27 mm. 
From the Bahamas and the West Indies to Rio de Janeiro; Liberia (?). Rio Bayamon, above 
Palo Seco, 2 females; Hucares, 4 males. 
Uca pugnax rapax (Smith). 
Gelasimus rapax Smith, Trans. Conn. Acad. Sci., it, 134, pi. it, f. 2, pi. iv, f. 3, 1870. 
Front with arcuate margin; width at base or posteriorly about two-sevenths the width between 
anterior angles of carapace. Lateral margin curved inward anteriorly, forming acute angles. Palm 
proportionally shorter and proximally broader than in U. mordax; the oblique ridge on its lower inner 
surface is formed of large tubercles and does not terminate so near the carpus as in U. mordax , and 
consequently is more oblique to the lower margin. The two rows of tubercles at base of daetylus are 
near together and subparallel. Smaller than U. mordax , usually less than an inch in width. Measure- 
ments of male from Boqueron Bay: Length, 14.5 mm.; width, 22.5 mm. 
The subspecies which I designate under the name of Uca pugnax rapax is a West Indian form of 
fiddler, differing from the common U. pugnax of the east coast of the United States chiefly as follows: 
In U. pugnax the superior orbital border or eyebrow is nearly vertical and barely visible in a dorsal 
view, while in U. pugnax rapax the eyebrow is more oblique and readily visible from above. In U. 
pugnax the space between the daetylus and carpal cavity is coarsely granulate; in U. pugnax rapax finely 
granulate. 
Florida Keys to Rio de Janeiro. In Porto Rico at Catano; San Juan; Boqueron Bay, very 
numerous; Ensenada Honda, Culebra; Hucares, numerous; Fajardo. 
The typical form of U. pugnax extends from Provincetown , Mass., to Georgia. 
Frequents salt marshes. Taken in the mangrove swamps at San Juan Bay, Porto Rico. 
Uca leptodactyla Rathbun. 
Uca leptodactyla (Gufirin ms.) Rathbun in Rankin, Ann. N. Y. Acad. Sci., xi, 227, 1898. 
A s lall spec.cs, a little over a third of an inch wide, thicker and more cylindrical than any other 
of the Porto Rican species of Uca. The front at its base or posteriorly is about one-fourth the width 
between anterior angles of carapace. These angles are directed obliquely outward. The oblique ridge 
on lower half of inner surface of palm does not terminate at the carpal cavity, but is continued by an 
angular turn to near the superior margin of palm. This upper half of the ridge is parallel to the 
tubercular ridge at base of daetylus. Fingers of great claw very slender and delicate. Ambulatory 
legs light colored and marked with small dark spots, which form in part transverse bands. 
Length of male from San Juan, 6 mm.; width, 9.8 mm. 
Bahamas and West Indies to Santos, Brazil. Porto Rico: San Antonio Bridge, San Juan; Boque- 
ron Bay; Ensenada Honda, Culebra; Fajardo. 
Uca thayeri Rathbun. 
Uca thayeri Rathbun, Proc. Washington Acad. Sci., ii, 134, pi. viii, figs. 1 and 2, 1900. 
Carapace very broad in its anterior fourth, narrowing rapidly in its posterior three-fourths; 
antero-lateral angles almost rectangular, 1 ilunt ; sometimes the carapace is narrower at orbital angles than 
a little behind that point, caused by the curving inward at lateral angle of one or both lateral margins. 
Dorsal furrows deep, especially the cervical and the transverse gastro-cardiac furrow; less deep are the 
obliquely longitudinal branchial furrow and the postorbital. Surface finely and densely Granulate 
through the lens, and tomentose, the hair retaining particles of mud. Front very narrow, not linear 
nor spatuliform, but subtriangular, at base or posteriorly less than one-fifth the width between the 
antero-lateral angles of the carapace, anteriorly truncate or nearly so; sides oblique and almost straight; 
