124 Fitst Annual Report 
sharp and short. Uropoda about half the length of the body, 11 
mm.; peduncle 3.5 mm., and about two-thirds as long as the outer 
ramus; outer ramus slightly shorter than inner, which is armed with 
a single spine. 
Alloniscus perconvexus Dana 
(Figure 69) 
Locality—Abundant in sand of upper beach under kelp; very 
abundant at high tides when driven out by the water. 
Color—Dull gray mottled with black and white. 
Body ovate and convex, about twice as long as wide, 15 mm. by 
7 mm. Head has frontal margin produced in the middle into a 
rounded lobe; antero-lateral angles into an acute process extending 
slightly beyond the eyes. Eyes composite and situated close to 
lateral margins. First pair of antenne very small and rudimentary, 
consisting of three small articles. Second antenne composed of five 
articles and a flagellum. First two articles short, third and fourth 
longer and subequal, fifth over one and a half times as long as fourth. 
Flagellum has three subequal articles. Second antenne thickly cov- 
ered with small spines. Maxillipeds have a palp of three articles. 
Palp of mandible wanting. 
First segment of thorax longer than the others, which are sub- 
equal. On the first segment of the thorax a faint suture line extends 
a short distance from the posterior margin and at an obtuse angle, 
indicating the epimeron. On the next three segments sutures extend 
the length of the segments. On the last three segments epimera are 
not visible. Legs ambulatory, thickly spined. 
Abdomen consists of six segments, five subequal in length, the 
sixth somewhat longer. First two are covered laterally by the last 
thoracic segment. Last abdominal segment triangular and narrower 
than all the preceding segments. Uropoda very short, about the 
length of last abdominal segment; inner branch about half as long 
as outer. 
The whole surface of the body is covered with minute spines. 
Idothea rectilinea Lockington 
(Figure 70) 
Locality—Abundant in pools, under rocks, on Phyllospadix and 
among fucus at low tide. 
Color—Male usually a light brown; female usually a very dark 
brown with antenne and legs of light brown. 
Body narrow and elongate; sides almost parellel and segments 
very closely articulated; five times longer than wide, 20 mm. by 4 
mm. Dorsum depressed longitudinally on either side of median line. 
