106 STALK-EYED CRUSTACEA. 
the second antenne distinguishes Calastacus from Calocaris. The second 
antenna of Calocaris macandree is represented on Plate XXVIL., Fig. 2, 2%, 
for comparison with the same organ of Calastacus (Fig. 1°). 
Calastacus stilirostris Fax. 
Plate XX VII., Fig. 1-1’. 
Bull. Mus. Comp. Zool. XXIV. 194, 1893. 
Male. — Carapace laterally compressed, naked, punctate ; rostrum long, 
narrow, acute, apex slightly upturned ; two strong spines directed upward 
and forward at the base of the rostrum; from the root of the rostrum the 
median dorsal line of the carapace is very convex; a light median carina 
runs along the back from the base of the rostrum, fading out before reach- 
ing the hind border of the carapace. The gastric area is lightly corrugated 
on each side of the carina. Abdomen longer than the carapace (including 
the rostrum), naked, smooth; first segment small, with rudimentary pleural 
projections ; pleure of the succeeding segments broad, rounded, and bent 
outward ; telson long, quadrangular, with convex hind border. 
_ Eyes rudimentary, subglobose, devoid of pigment and corneal facets. 
Peduncle of first antenna composed of three stout segments, decreasing in 
size successively from the first to the third. Basal segment of second an- 
tenna provided with a sharp spine on inner edge of lower side; second 
segment armed with a long and sharp distal external spine (stylocerite) ; 
from between the base of this spine and the following segment springs a 
slender, sharp, articulated spine (scaphocerite) which nearly reaches the 
end of the succeeding segment; inner edge of the second joint also carries 
a median and a distal spinule, the latter of which is the larger; the third 
and fourth segments are unarmed, the latter short and carrying a long 
flagellum, which exceeds the whole length of the body. Epistome largely 
developed, terminating anteriorly in a triangular process at the base of the 
antennules. 
Chelipeds long, symmetrical on the two sides; coxa furnished with a 
small spine on the anterior border of the distal end; the ischium has from 
one to four spines on the lower margin; merus laterally compressed, armed 
with a spine on the upper edge near the distal end, and a variable number 
of spines (four to eight) on the lower edge; one of these, near the distal 
end of the segment, is very long; there is also a small spine on the ex- 
