44 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Family P 0 RTUNID 4 t Leach, 1819; Miers, 1886. 
Carapace depressed, moderately transverse, and usually widest at the last anterolateral marginal 
spine. Front horizontal. Orbits and eye-stalks of moderate length. Lateral teeth usually from five to 
nine. Last trunk legs usually adapted for swimming, with terminal joint ovate, flatly expanded. 
Key to the Porto Rican genera of the family Portunidse. 
A. Movable portion of antennae not excluded from orbit. 
B. A longitudinal ridge on the palate. 
0. Outer maxillipeds not remarkably advanced; segments of palp subcylindrical. 
D. Abdomen of male triangular Portunus 
D'. Abdomen of male X'Shaped - Callinectes 
O'. Outer maxillipeds remarkably advanced; last two segments of palp compressed and lamellate Liipclla 
B'. No longitudinal ridge on the palate Arenxus 
A'. Movable portion of the antenna excluded from orbital cavity by a prolongation of basal joint of antenna . . Charybdella 
Genus PORTUNUS Fabricius. 
PorCunvs Fabricius, Entom. Sys., Suppl., 325, 1798. 
Lupn Leach, Edin. Encyc., vii, 390, 1814. (Not Lupa de Haan, 1883.) 
Lupania Rafinesque, Amer. Monthly Mag., m, 272, Aug., 1818. 
Neptunus de Haan, Fauna Japon., pp. 3 and 7, 1833. 
Carapace transverse, usually broad, and depressed or little convex, often with surface areolated. 
Front proper well delimited from inner supra-orbital angles and cut into from three to six — usually 
four — teeth; its breadth is from a sixth to a fifth the greatest breadth of carapace (lateral epibranchiai 
spines not included). Antero-lateral borders oblique, arched, longer than postero-lateral, cut into 
nine teeth (including outer orbital angle), of which the ninth may be enlarged. The orbit usually 
has two fissures or sutures in upper border, which border is less prominent than lower border, so 
that the orbit very often has a dorsal inclination; the lower border has a fissure or suture near the 
outer angle, inner angle dentiform and usually very prominent. The antennules fold transversely. 
The basal antennal joint is peculiarly short and has its antero-external angle produced to form a lobule 
or spine extending into the orbit; the flagellum, of moderate length, stands in orbital hiatus. Epistome 
short or even linear, sometimes prolonged in middle line to form a spine lying below interantennulary 
septum. Buccal cavity squarish, broader than long, efferent branchial channels almost always well 
defined. Palpus of outer maxillipeds subcylindrical. Chelipeds longer, usually much longer than any 
of legs, and massive; arm with spines; both inner and outer angles of wrist spiniform; palm prismatic, 
costate, and usually with spines, fingers usually nearly as long as the palm and strongly toothed. 
Ambulatory legs compressed; in last pair merus and carpus are short and broad; propodus and dactylus 
typically foliaceous and paddle-like for swimming. Abdomen of male triangular, five-jointed, the 
third, fourth, and fifth segments being fused; the first segment in both sexes is almost entirely concealed 
beneath carapace. 
A. Carapace wide; antero-lateral margin the arc of a circle with long radius, whose center is near posterior 
margin of carapace , '. Subgenus Portunus 
B. First eight lateral spines or teeth subequal .ventralis 
B'. Second, fourth and sixth lateral spines or teeth smaller than the others sulcatus 
A'. Carapace narrow; antero-lateral margin the arc of a circle with short radius, whose center is near center of 
cardiac region Subgenus Aclielous 
B. Carapace with rounding posterior corners. 
C. No spine on the basal joint of swimming feet. 
D. Superior outer surface of manus with a longitudinal tuberculated ridge. 
E. Frontal teeth six (exclusive of the inner orbital) spinimanus 
E'. Frontal teeth four (exclusive of inner orbital)., depressifrons 
D'. Superior outer surface of manus iridescent, and without a longitudinal tuberculated ridge ordioayi 
C'. An erect spine on the basal joint of swimming feet sebas 
B'. Carapace with sharp posterior angles - - . spinicarpus 
Subgenus PORTUNUS. 
Carapace very wide, the antero-lateral margin being the arc of a circle with long radius, whose 
center is near posterior margin of carapace. Last spine of antero-lateral margin usually much larger 
and longer than the others. 
