108 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Alpheus rostratipes Pocock. 
Alpheus rostralipes Pocock, Jour. Linn. Soc. London, Zool., xx, 522, 1890. 
Carapace cristate between eyes; rostrum spiniform, not reaching second antennular segment. 
Margin of orbits rounded. Segments of antennular peduncle subequal in length; spine of scale reaching 
to middle of second segment. Antennal scale equal in length to antennular peduncle; scale with a 
very broad blade, much shorter than its spine. Antennal peduncle a little longer than antennular; 
basal spine about as advanced as antennular scale. Merus of large chewed with a sharp tooth at distal 
end of superior margin. Propodus compressed, subovate, much higher than fingers; slightly twisted; 
distal half of outer face with two longitudinal grooves which cqn verge toward thumb; upper margin 
with a shallow groove. Thumb extremely short; dactylus less than one-third the length of palm. 
Fingers of smaller c.heliped longer than palm. Thumb twice as wide at base as dactylus. Carpal joints 
of second pair becoming progressively shorter in the following order: First, fifth, second, third, fourth. 
A small species, a female with eggs measuring 10.5 mm. in length. 
Arroyo, Porto Rico. Type locality, Fernando Noronha (Pocock). 
Alpheus armatus, sp. nov. 
Carapace of female compressed, high, the height being equal to length exclusive of rostrum; 
smooth. Rostrum extending nearly to the second segment of peduncle of antennulae; narrow, tip 
acuminate; depressed, upper surface concave from behind 
forward, lateral margins fringed with bristles; a short blunt 
median spine at base on a line with bases of eye-stalks; ros- 
trum separated from eye-stalks by a deep groove. Between 
the base of rostrum and inner base of eye-stalk on each side is 
a long spine with slender tip; tips convergent, rising a little 
above level of adjacent part of rostrum and not reaching ex- 
tremity of eyes. Although the eye-stalks are plainly visible, 
they are entirely covered by an extension of carapace; cornea 
large and dark-colored, obtusely pointed in front. Anterior 
margin of carapace external to the eyes entire. The spine of 
antennular scale is slender and extends about as far forward 
as the rostrum. Second joint of peduncle about twice as long 
as third joint. Outer branch of flagellum thick except at 
extremity, and a little longer than peduncle; inner branch 
slender and three times as long as outer. The antennal scale 
nearly as long as antennular peduncle. It is rounded at the 
end and lias a slender spine separated from the blade by a 
narrow slit extending half the length of the scale; a short 
spine at its outer inferior base. Peduncle a little longer than 
that of antennula; flagellum longer than body. The external 
maxillipeds reach, when extended, as far as end of antennular 
peduncle; they are clothed with long hairs. 
First pair of feet missing in type specimen; second pair 
slender (right one present) and as long as outer antennular flagellum; ischium and merus subequal; 
first joint of carpus about two-thirds as long as merus; second joint half as long as first, a trifle longer 
than fifth, and twice as long as third or fourth, which are subequal. Digits about equal to palm and 
also to last carpal joint. The third foot reaches about to last carpal joint of second pair. Merus three 
times as long as ischium and twice as long as carpus; it has an inferior distal spine, Propodus 
somewhat shorter than merus, its inferior margin bordered by nine long slender spines. Dactylus 
short, about one-fourth propodus, curved, with a slender nail. Fourth and fifth pairs of feet similar to 
third, but slenderer and shorter; in the fifth pair there are but six propodal spines. 
Abdomen smooth and rather short and thick. The telson has two pairs of spines on its dorsal 
face; extremity slightly arcuate, with a spine on either side. Lateral laminae subequal in length and 
longer than telson; inner branch suboval and unarmed; outer branch with an irregular transverse 
suture and a long black spine near outer terminal angle. Basal scale of uropods two-spined. 
terior' portion, 
X 4. 
X 4. ( b ) Small cheliped, 
