PARATANAIS. RIGIDUS. 141 
ISOPODA,. TANAID&. 
ABERRANTIA. 

PARATANAIS RIGIDUS. 
Specific character.—Body narrow. Margins of the pereion and pleon 
parallel, pleon terminating in a central point. Antenne not longer than the 
cephalon. Posterior pleopoda having both rami uniarticulate, the outer 
being half the length of the inner, 
Length 2th of an inch. 
Tue form of this species is slender and cylindrical, 
. the sides running parallel with each other from the outer 
angle of the anterior margin of the head almost to the 
posterior pair of pleopoda. The cephalon is confluent 
with the first segment of the pereion, and both together 
form a segment that is scarcely longer than broad. The 
second segment of the pereion is very short; the third is 
about three times as long as the second, and both together 
about as long as the cephalon; the fourth segment is 
quadrate, and as long as the two preceding ; the fifth is a 
e oo = et IT Stn 0 oe Wyo (I, S 
