6 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Key to the Porto Rican genera of the family Ocypodidx. 
A. Carapace trapezoidal or quadrate. Eye-stalks elongate. 
B. Lateral margins entire. 
C. Eye peduncles stout; chel* in male somewhat unequal Ocypode 
C'. Eye peduncles slender; chelte in male extremely unequal Urn 
B'. Lateral margins toothed. 
C. Antennse excluded from the orbit by internal suborbital lobe Euryplax 
C'. Antennse not excluded from the orbit Tetfaplax 
A'. Carapace with antero-lateral margins arcuate. Eye-stalks of moderate length. 
B. Carapace rectangular posteriorly. 
C. Antero-lateral margin not dentate Chasmocarcmus 
C'. Antero-lateral margin dentate Speocarcinus 
B'. Carapace cancroid in form: postero-lateral margins converging posteriorly. 
C. Chelipeds with palm more or less angular. Fingers elongate . Eucratopsis 
C'. Chelipeds with palm robust. Fingers short Panoplax 
Genus OCYPODE Fabricius. 
Ocypode Fabricius, Entom. Sys., Suppl., 312, 1798. 
Orbits very large and open, extending all along the anterior margin on either side of the narrow 
and deflexed front. Eye-stalks large, the large cornea: covering much of the lower surface of this 
terminal joint. Chelipeds in the adult male are unequal and well developed, and the palm has a ver- 
tical series of short raised lines or tubercles on the inner surface, which form a stridulating ridge. 
‘ Ocypode albicans Bose. Sand Crab; Ghost Crab. 
Ocypoda albicans Bose, Hist. Nat. Crust., I, 196, pi. 4, f. 1, 1S02. 
Ocypode arenarius Say, Jour. Pliila. Acad. Sci., I, 69, 1817. 
Ocypode arenaria Miers, Ann. Mag. Nat. Hist. (5), x, 384, pi. xvii, figs. 7, 7 a, lb, 1882; Rathbun, Ann. Inst. Jamaica, I, 26, 1897. 
Ocypode albicans Rathbun, Proc. Wash. Acad. Sci., IT, 134, 1900. 
Carapace coarsely granulate toward the sides, finely granulate on middle and posterior portions. 
Antero-lateral angles acute and prominent. Eyes rounded at the distal extremity. Stridulating ridge 
narrow, tuberculate. Ambulatory legs compressed, with long, yellow, marginal hairs. 
Dimensions of male from Nassau: Length, 34 mm.; width, 41 mm. 
From Long Island to Brazil; Bermudas. Porto Rico (Gundlach). Taken by the Fish Hawk party 
at Nassau, Bahamas, and the following Porto Rican localities: San Juan, Aguadilla, Puerto Real, Playa 
de Ponce, Hucares, Fajardo, and Ensenada Honda, Culebra. 
The Ocypode rhombea listed by Gundlach probably does not. differ specifically from his Ocypode 
arenaria. 
Found on sandy beaches, where they dig holes at and above high-water mark. They live on 
refuse thrown up by the tide, and are partly nocturnal. Their color is that, of the sand, and they 
are very swift of movement. 
Genus UCA Leach. Fiddler Crabs. 
Uca Leach, Ediu.Encyc.,vn, 430, 1814 (not Uca Latreille, 1819): Rathbun. Proc. Biol. Soc. Wash., xi, 154, 1897. 
Gelasimus Latreille, Nouv. Diet. Hist. Nat.., xii, 517, 1817. 
Orbits extending all along the anterior margin of the carapace on either side of the comparatively 
narrow front. Eye-stalks long and slender. Chelipeds in the adult male strikingly unequal; iu the 
female small and equal. 
Key to the Porto Rican species of the genus Uca . 1 
A. Front wide, for the genus. 
B. Oblique ridge on inner surface of palm terminating at carpal cavity. 
C. The two rows of tubercles on inner surface of palm at base of dactyius are divergent from below upward 
and leave a considerable space between them mordax 
C'. The two rows of tubercles at base of dactyius are subparallel and near together .pugnax rapax 
B'. Oblique ridge not terminating at carpal cavity, but continued to near superior margin of palm leptodactyla 
A. Front very narrow, but not linear nor spatuliform thayeri 
1 Gundlach recognizes the presence of the fiddler crab in Porto Rico under the name “ Gelasimus vocator.” 
