THE BRACHYURA AND MACRURA OF PORTO RICO. 
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Family HIPPOLYTID/F Bate, 1888. 
Rostrum of important size; eyes not covered by carapace; the mandibles may have a cutting edge 
and palp, or be without one or both; first pair of trunk-legs with moderate-sized chelfe; second pair 
chelate, with the wrist or fifth joint sometimes much and sometimes little subdivided. 
Key to the Porto Rican genera of the family Hippolytidse. 
A. Carpus of second pair of feet composed of few segments. 
B. Rostrum large. Carpus of second pair of feet biarticulate or triarticulate. 
C. Carpus biarticulate. Rostrum suborbicular Platybema 
C'. Carpus triarticulate. 
D. Rostrum cultriform Latreutes 
D'. Rostrum very slender Tozeuma 
B'. Rostrum very short. Carpus five-articulate Thor 
A'. Carpus of second pair of feet composed of many segments Hippolysmata 
Genus PLATYBEMA Bate. 
Cyclorhynchus de Haan, Fauna Japon., 174, 1849. (Name preoccupied.) 
Rhynchocyclus Stimpson, Proc. Acad. Nat. Sci. Phila., xu, 27 ( 96), 1860. (Name preoccupied.) 
Platybema Bate, Challenger Rept., Zool., xxiv, 576, 578, 1888. 
Carapace dorsally carinated, produced anteriorly to a large, laterally compressed, deep rostrum, 
which projects below level of dorsal ridge. Pleon generally, but slightly, compressed laterally, having 
the lateral coxal plates iargely developed. Eye-stalks short, stout. First pair of antennae short, peduncle 
not reaching to end of scaphocerite ; flagella two, short, extending but little beyond extremity of rostrum. 
Second pair of antennae having a short and broad scale that narrows toward extremity, is armed with 
a small tooth on outer margin and fringed with long hairs on inner, and does not reach beyond 
extremity of rostrum; flagellum about one-half the length of the animal. Mandibles short, strong, 
cylindrical, without cutting edge or palp. Second maxillipeds six-jointed. First and second pairs 
of thoracic feet short; first pair robust, having the carpus short and anteriorly excavate to receive 
extremity of propodus, which articulates with it at the infero-distal angle; second pair slender, carpus 
biarticulate. Pleopoda biramose, foliaceous, unequal. Telson triangular. 
Platybema rugosum Bate. 
Platybema rugosus Bate, Challenger Rept., Zool., xxiv, 579, pi. civ, f. 2, 1888. 
Platybema rugosum Ortmann, Dec. u. Schiz. Plankton-Exp., 47, 1893. 
Robust and dorsally arcuate. Dorsal crest armed with teeth from posterior margin of carapace 
to under surface of distal extremity of rostrum; posterior teeth larger than rostral. Inner and outer 
canthus of orbit furnished with a small tooth. Fronto-lateral angle of carapace produced to a prominent 
point, the lateral walls adorned with spines or tubercles. A straight row of spines extends from 
fronto-lateral angle to posterior margin of carapace. The surface above this row is furnished with 
scattered spines. Pleon having the anterior two segments elevated in front so that, when viewed 
laterally, the elevations resemble teeth; the third and succeeding somites smooth, except sixth, which 
is dorsally armed with two transverse rows of spines, three across the middle and four on posterior 
margin. Telson having the lateral and distal margins furnished with small spines. 
Dimensions of ovigerous female: Length, 21 mm. ; length of carapace and rostrum, 9.5 mm. ; length 
of rostrum, 3 mm. 
Mayaguez, on coral reef; off Vieques Island, 16 fathoms, station 6092; off Culebra, 14f to 15 fathoms, 
stations 6086, 6093; off St. Thomas, 20 to 23 fathoms, station 6079. 
Bate ( loc. cit.) had one specimen said to come from off Culebra Island, 390 fathoms, but some 
doubt is cast on the correctness of this locality by the statement, on page 859 of the same work, that it 
w r as associated with Leptochela serratorbita at St. Thomas in shallow water. Ortmann (loc. cit.) has 
noted this discrepancy. 
Distribution: Gulf of Mexico, 25 to 38 fathoms, stations 2369 to 2374 (Albatross) and stations 5073 
and 5093 (Grampus); off Dry Tortugas, 26 fathoms, station 2414 (Albatross'); off Cape Catoche, Yucatan, 
24 fathoms, station 2365 ( Albatross); off mouth of Tocantins, 50 to 100 meters (Ortmann). 
2(1 — F. 0. B. 1900—8 
