DYNAMENRE, AL 7 
ISOPODA. SPHAROMIDA, 
NORMALIA. 
Genus—DYNAMENE.  (Leach.) 
Generic character. Smooth, not bristly; contractile into a 
ball, with the lateral appendages of the pleon exposed ; 
terminal segment having a deep excavation in the middle of 
the posterior margin. Superior antenne with the basal joint 
oblong, not flattened, and the second joint sub-triangular. 
THE species of this genus have much the appearance 
of small Sphzrome, but are distinguished from them 
by the slit at the extremity of the tail, which is simple, 
without a central tooth, as in Cymodocea, from which 
they also differ in the smooth clean aspect of the dorsal 
surface, and in the structure of the basal joints of the 
superior antenneze. 
The body is very convex, smooth, and destitute of the 
bristles which are so conspicuous in the Cymodocee. 
The upper antennz, when at rest, are concealed beneath 
a slightly produced margin to the front of the head; the 
basal joint is oblong and but slightly flattened, the 
second joint is triangular-shaped, and the flagellum is 
multiarticulated ; the lower antenne are more slender at 
the base than the upper, with four nearly equal basal 
joints, and a moderately long multiarticulate flagellum. 
The mandibular appendage has the two terminal joints 
subequal and strongly setose on the inner edge ; the apex 
of the mandible is armed with several minute denticulated 
teeth and a slender setigerous lobe in the middle of the 
apical edge; the foot-jaws have the intermediate joints 
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