52 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Tribe OXYRHYNCHA or MAIOIDEA. 
Carapace narrowed anteriorly and rostrate, with the hepatic regions small, the branchial large. 
Epistorne generally large. Buccal frame quadrate, with anterior margin straight. Nine pairs of 
branchiae, with the efferent channels opening at the sides of the endostome. The afferent channels 
open behind the pterygostomian regions, in front of the bases of the chelipeds. First antennae longi- 
tudinally folded. Third maxillipeds with the fifth joint articulated at the apex or at the front inner 
angle of the fourth. Genital organs of male inserted at bases of last pair of trunk legs. 
Family MAIIDAi Leach, 1 N 1 ■>. 
Basal joint, of antennae well developed. Chelipeds usually not a great deal longer or more mas- 
sive than the other legs. 
Key lu the Porto Rican genera of the family Maiidx. 
A. Basal joint of antenna 1 extremely slender throughout and usually long. Eyes without orbits and not concealed. 
B. Carapace elongate, narrowed in front. External maxillipeds somewhat pediform, with the palp large and 
coarse, the uterus often narrower than ischium. Basal joint of antennae usually subcylindrical. 
C. Rostrum extremely long. Dactyli of ambulatory legs longer than the propodi StenorynChus 
O'. Rostrum short. Dactyli of ambulatory legs shorter than the propodi Podocliela 
B'. Carapace usually subtriangular. External maxillipeds with the merus at least as broad as ischium and 
the palp small. Basal joint of antenme flattened or concave ventrallv. 
C. No postocular spine or tooth Aminas 
C'. A postocuiar spine or tooth. 
D. Eye-stalks long and slender Ewcinet.ops 
D'. Eye-stalks not long and slender. 
E. Carapace depressed, the branchial regions considerably flattened posteriorly and laterally, so that their 
lateral margins are visible from above for nearly their whole length. 
F. Postocular spine usually large. Hepatic region rather remote from the eye Colludes 
E'. Postocular spine small. Hepatic region approximating the eye Balrachonotus 
E'. Carapace higher and more convex, branchial regions not remarkably flattened, their lateral margins 
for the most part invisible in a dorsal view. 
F. Rostrum bifid or notched Enpiognatha 
F'. Rostrum simple. 
G. No spine on upper margin of orbit -Inasimus 
G'. A spine on upper margin of orbit tnachoides 
A'. Basal joint of antenme not extremely slender, often very broad. Eyes with orbits, or capable of concealment. 
B. Basal joint of antennae truncate-triangular. Eyes without true orbits; eye-stalks very short, concealed 
beneath a supraocular spine. 
C. Antennae concealed beneath the rostrum Epialtus 
( Antennae not concealed beneath the rostrum Aeanilumyx 
h' . Basal joint broad, usually either extensively produced outward or with t or 2 distal spines. Eyes with orbits. 
C. Orbits rudimentary, with a large, blunt, cupped postocuiar process into which the eye is retractile, but 
is not completely concealed. Eye-stalks short. 
D. Carapace oval-oblong ; CUunnas 
D'. Carapace subtriangular. 
E. Carapace armed with spines or prominent tubercles Scyramalhia 
E'. Carapace almost smooth Pella 
C'. Orbits complete, often tubular, completely concealing retracted eye. 
D. Meral joints of ambulatory legs with continuous laminate expansions. 
E. Carapace very high in middle; height greater than half the width .Hem us 
E'. Carapace not high; height less than half the width T/ioe 
It'. Meral joints of ambulatory legs without continuous laminate expansions. 
E. Fingers spoon -shaped at tips. 
F. Carapace suboblong or suboval, very broad in front. Orbits directed forward Pilhu 
F'. Carapace subtriangular, narrow in front. Orbits directly obliquely forward. 
G. Orbits entire Telcuphrys 
G'. Orbits dentate or spined Hithrax 
E'. Fingers acute at tips. 
F. Carapace with a series of lateral spines or teeth SCenocionops 
F'. Carapace without a series of lateral spines or teeth. 
G. Rostral horns contiguous. 
H. Horns long and slender Lcptopisa 
It'. Horns short, broad and flat Lissa 
G'. Rostral horns not contiguous. 
It. Preorbital spine extremely long Picroceroides 
H'. Preorbital spine not extremely long. 
J. Orbits tubular, projecting Macrocceloma 
J'. Orbits with closed fissures, but not distinctly tubular and projecting Jlicrophrys 
