THE BRACHYURA AND MACRURA OF PORTO RICO. 
95 
Family AX 1 IIDE Bate, 1888. 
Carapace produced to a horizontally flattened point or rostrum. First pair of trunk-legs chelate 
and subequal; second pair small, chelate, equal; last three pairs simple. First segment of pleon very 
short. Swimming-fan strong. The outer branch of uropods not longer than the inner. Branchiae 
filamentous, cylindrical, and compressed. 
Genus AXIUS Leach. 
Axius Leach, Trans. Linn. Soc. London, xi, 343, 1815. 
Second joint of outer antennae with a small, movable spine or scale. 
Key to the Porto Rican species of the genus Axius. 
A. Rostrum with sides unarmed except at the base defensus 
A'. Rostrum armed on one side with three spines, on the other with two .insequalis 
Axius defensus, sp. nov. 
Carapace of female nearly tivice as long as high, finely pubescent. Rostrum, long, narrow, acumi- 
nate, spiniform, and slightly upturned at tip, armed at base on either side with a sharp spine pointing 
obliquely forward and upward, just above eye. 
A small spine above antenna on anterior margin 
of carapace. From edge of rostrum a sharp lateral 
carina runs backward on each side about two- 
thirds the way to cervical suture, armed in its 
anterior half with two spines, the anterior the 
larger. The median carina extends to cervical su- 
ture, though its posterior fourth is faintly marked; 
there is a spine at its middle, which is broken off 
short in the unique specimen. Between the 
median and lateral crests is a submedian crest 
intermediate in length and armed with seven or 
eight irregular spines. 
Eyes on short stalks, which are nearly con- 
cealed by the rostrum; cornea large and black. 
Peduncle of antennula overreaches rostrum by 
length of its last segment; flagella subequal in 
length and about equal to length of carapace. 
Distal spine on second segment of antenna at base 
of acicle very short, not extending beyond end of 
second segment. The acicle is a little longer, but 
also very short, not more than one-fifth the length 
of fourth segment, and has a small spine at its 
inner base. Fifth segment about half as long as fourth. Flagellum nearly twice as long as carapace. 
Ischium and merus of external maxilliped armed on lower edge with spines, the distal two of which 
are long and slender; these joints have also an inner spinous crest. 
Chelipeds equal, about 1.5 times as long as the carapace; chelae about two-thirds as long 
as the carapace. Ischium and merus armed below with spines; merus with a spine on its upper edge 
at distal third. Carpus a little longer than wide. Propodus compressed, with sharp edges, about 
two-fifths as wide as length of palm; margins subparallel; upper margin with a small distal spine. 
Fingers about two-thirds the length of palm, slender, tips crossing, prehensile edges finely denticulate. 
The second pair of legs are slender and do not reach half the length of palm of first pair. Ischium 
two-fifths the length of merus; carpus three-fifths the length of merus; ischium and merus armed below 
with a few spines irregularly placed. Propodus a little longer than carpus, the fingers nearly as long 
as palm. Third and fourth pairs of legs nearly alike and longer and slenderer than the second. Carpus 
about half as long as propodus and two-fifths as long as merus. Dactylus about two-fifths as long as 
Fig. 17 . — Axius defensus, female, (a) Anterior portion, x 5. 
( b ) Right cheliped, x 3.5. 
