14 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Key to the Porto Rican genera of the fam ily Gecarcinidee. 
A. Palpus of outer maxillipeds inserted on inner face of merus near its summit and concealed under the joint.. . Gecarcinus 
A'. Palpus of outer maxillipeds inserted at external angle of merus and exposed to view. 
B. Inner edges tf schiunt and merus of outer maxillipeds in one line Ucicles 
B'. Inner edges of ischium and merus of outer maxillipeds forming a reentering angle Cardisoma 
Genus GECARCINUS Leach. 
Gecarcinus Leach, Edin. Encyc., vn, 130, 1814. 
Carapace oval, not high, but much swollen laterally; lateral margin not distinctly marked. Front 
very strongly recurved downward. Orbits deep, oval, and without a notch on the external margin. 
Inner antennae almost entirely concealed under the front. Buccal cavity nearly circular. External 
maxillipeds very wide, with a wide space between them; the merus as large as the ischium, and covers 
entirely the small, two-jointed palpus which is inserted on its inner face. Margins of feet armed with 
spiniform teeth. 
Gecarcinus lateralis (Freminville). 
Ocypoda lateralis Freminville, Ann. Sci. Nat. (2), in, 224, 1835. 
Gecarcinus lateralis Gu6rin, Icon. Regne Anim., pi. v, 1. 1. 
Carapace four-fifths as long as wide. Median and cervical sutures deep. Lateral border with a 
few spinules near orbit. Lower margin of orbit denticulate. Inner border of merus of outer maxil- 
lipeds without a distinct notch. Chelipeds very unequal; carpus without teeth on its inner margin. 
Fingers gaping. Dactyli of ambulatory legs armed with four rows of spines. 
Length of male, Vieques, 40.3 mm. ; width, 50 mm. ; width between outer orbital angles, 25.6 mm. ; 
width of front near lower margin, 10.5 mm. 
Bahamas; Florida Keys to United States of Colombia and Venezuela; Bermudas. Porto Rico: 
Arroyo, under logs on land 20 feet above high water; Caballo Blanco Reef, Vieques; Mayaguez 
( Gundlach ) . 
Genus UCIDES Rathbun. 
Uca Latreille, Nouv. Diet. Hist. Nat., xxxv, 96, 1819 (not Uca Leach, 1814). 
Ucides Rathbun, Proc. Biol. Soc. Wash., xi, 154, June 9, 1897. 
Oedipleura Ortmann, Zool. Jahrb., Syst., x, 334, 1897. 
Carapace oval and very high. Front very narrow, strongly inclined and almost semicircular. 
Orbits rather large and open outside below the external angle. Buccal cavity of rhomboidal form; 
merus and ischium of external maxillipeds quadrilateral, almost the same size, with a straight inner 
border. Palpus articulated at outer angle of merus and applied against its anterior border. Dactyli of 
ambulatory legs not spinous. 
Ucides cordatus (Linnaeus). Plate 1. 
Cancer cordatus Linnaeus, Amcen. Acad., vi, 414, 1763. 
Ucides cordatus Rathbun, Ann. Inst. Jamaica, 1 , 25, 1897, and synonymy. 
Carapace of male three-fourths as long as broad. Lateral margin a line of indistinct granules. 
Chelipeds very unequal, the larger one very long and strong, both armed on inner surface with strong 
spines, especially along margins; fingers spoon-shaped at tips, those of large chela widely gaping. 
Ambulatory legs densely fringed with long hair. Female considerably narrower than male; lateral 
marginal line very prominent; chelipeds short and subequal; ambulatory legs sparsely hairy. 
Length of male, Rio de Janeiro, 54 mm.; width, 70 mm. ; width between outer orbital angles, 
43.4 mm. Length of female, San Juan, 32 mm.; width, 40.5 mm.; width between outer orbital angles, 
28.5 mm. 
Porto Rico: San Juan; Rio Bayamon, above Palo Seco; Porto Rico (Gundlach). Cuba; Jamaica; 
St. Thomas; Surinam; Brazil. 
Genus CARDISOMA Latreille. 
Cardisoma Latreille, Encyc. M6th., Hist. Nat., Insectes, x, 685, 1825. 
Carapace very high, squarish. Front very wide and almost straight. Buccal cavity in the form 
of an elongated square. The ischium of the external maxillipeds is narrow anteriorly, and the merus, 
a little shorter than the ischium, widens from behind forward in such a way as to form between the 
maxillipeds a rhomboidal space; the merus is almost heart-shaped, is cut on its anterior border, and 
has the palpus inserted at its external angle; the palpus is exposed to view. Dactyli of ambulatory 
legs very spinous. 
