28 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
culiform teeth. Front feebly divided into two lobes, nearly straight and with a tuberculiform tooth at 
the outer angle. Pterygostomian regions and merus of the outer maxillipeds granulose and rugose. 
Chelipeds strong, unequal, their upper surface rugose and eroded. Wrist with two tubercles at 
inner angle. Fingers strong, pointed, gaping in large cheliped. 
Color, light purplish red, bright red, or orange red; lingers black. 
Dimensions of male: Length, 14.5 mm.; width, 22.8 mm.; fronto-orbital width, 9.5 mm. ; frontal 
width, 5 mm. Greatest width at antepenult tooth of lateral margin. 
Bahamas; Florida Keys to Brazil; Bermudas. Porto Rico: Cabal lo Blanco Reef, Vieques; 
Hucares; Fajardo; San Juan (Gundlaeh). 
Genus EUPANOPEUS Rathbun. Mud Crabs. 
Panopeus Milne Edwards, Hist, Nat. Crust., I, 403, 1834. (Name preoccupied.) 
Eupanopeus Rathbun. Bull. Labor, Nat, Hist. State Univ. Iowa, iv, 273, 1898. 
Carapace of moderate width, length two-thirds to three-fourths the width, moderately convex, 
the regions fairly well delimited, crossed by broken transverse lines on anterior half. Antero-latera) 
borders horizontal or slightly^ upturned, shorter than postero-lateral, arcuate, tending to subquadrate, 
cut into five teeth, including orbital angle, which is more or less fused with the next tooth; the third, 
fourth, and fifth are usually well-marked and distinctly dentiform; outer margin of all the teeth 
sublam inar; postero-lateral borders moderately convergent, straight. Fronto-orbital border more than 
half the greatest width of carapace. Front between a third and a fourth the greatest width of carapace. 
Front horizontal or slightly deflexed, laminar, with a median notch, and two sinuous lobes, separated 
from the more elevated inner angle of orbit by a notch. Orbital margin with two small but distinct 
V-shaped notches above, continued backward by closed fissures, and a broad notch below outer angle. 
A prominent tooth at lower inner angle. Orbits transversely oblong, not tightly filled by the eyes. 
Inner portion of anterior margin of basal joint touches the front; outer angle of joint is prolonged 
into the broad orbital hiatus, but does not exclude flagellum from orbit, Merus of outer maxillipeds 
transverse, its anterior margin more or less sinuous. Chelipeds unequal in both sexes; the merus has 
a superior subterminal tooth; the carpus a tooth at the inner angle; fingers acute; movable finger of 
large cheliped with large basal tooth. Legs rather thick, compressed. Abdomen of male 5-segmented. 
Key to the Porto Rican species of the genus Eupanopeus. 
A. A distinct groove along anterior margin of carpus of cheliped. 
B. Front grooved. Third segment of abdomen of male not reaching coxal joints of fifth pair of feet bennudensis 
B'. Front not grooved. Third segment of abdomen of male reaching the coxal joints. 
C. Second antero-lateral tooth broad, lobiform nccidentalis 
C'. Second antero-lateral tooth narrow, tuberculiform hnrttil 
A'. Carpal groove wanting or very indistinct, 
B. Width of carapace about 1.5 times length herbstii 
B'. Width of carapace about 1.3 times length americanus 
Eupanopeus herbstii (Milne Edwards). 
Panopeus herbstii Milne Edwards, Hist, Nat. Crust., i, 403, 1834; Benedict & Rathbun, Proc, U. s. Nat, Mus, xtv, 358, pi. xix. 
figs. 1 and 2, pi. XXIII, figs. 10-12, 1891. 
Eupanopeus herbstii Rathbun, Bull. Lab. Nat. Hist. State Univ. Iowa, iv, 273, 1898. 
Carapace nearly or quite 1.5 times as wide as long. Regions well marked, convexity variable, 
surface coarsely granulate. First (or orbital) tooth of lateral margin triangular, blunt, little prominent; 
second tooth separated from first by a shallow rounded sinus, and larger and nearly as advanced as 
first, either blunt-pointed and with arcuate outer margin, or lobiform; third and fourth teeth still larger, 
prominent, with arcuate outer margins and acute tips, the third directed obliquely inward, the fourth 
forward or slightly inward; fifth tooth shorter, with acute tip and straight outer margin; a transverse 
ridge continued inward from its anterior margin. Front about two-sevenths the greatest width of 
carapace; middle portion of margin advanced only a little beyond outer angles. Chelipeds heavy, 
granulate; carpus without a groove parallel to distal margin. Dark color of thumb in large chela 
continued more or less on palm. Third segment of abdomen of male reaching coxfe of fifth pair of feet; 
terminal segment oblong, rounded at end. 
A very large specimen measures 40 mm. long by 62 mm. wide; one of medium size, a female, is 
28mm. long, 40.6 mm. wide; fronto-orbital width, 23.2 mm.; width of front, 11.5 mm. 
From Rhode Island to Brazil; Bermudas. Porto Rico: San Juan; Puerto Real, in a mangrove 
swamp; reefs at Ponce; Ensenada Honda, Culebra; San Juan and Mayaguez (Gundlaeh). 
