CAPRELLA. 51 
derable time, and then suddenly stop, remaining perfectly 
motionless, not even moving their antenne.” 
They seldom attempt to swim, and will, when placed 
in the water independently of anything to rest upon, 
generally drop listlessly to the bottom. Mr. Gosse says, 
in his pleasant Naturalist’s Rambles on the Devonshire 
Coast, “ I have seen a large red species swim, throwing its 
body into a curve like the letter S, with the head bent 
down and the limbs turned back, the body being in an 
upright position. It was a most awkward attempt; and 
though there was much effort, there was little effect.” 
Kroyer has separated from this genus two others 
upon characters which appear to us to be very doubtful. 
The tail in Caprella is rudimentary, and exists in a semi- 
membranous condition. The development of this abnor- 
mally rudimentary part is, within small limits, variable. 
Upon the degree of its development Kroyer has founded 
the genera Podalirius and Afgina. It is only after a care- 
ful consideration of the structure of the animals that we 
have arrived at the conclusion that the establishment of 
these two genera is unnecessary. The genus Cercops also 
of Kroyer is mainly distinguished from Caprella by the 
small terminal abdomen being six-jointed and styliferous, 
but the second pair of legs have a vesicle at the base, as 
in Proto. ’ 
The geographical distribution of this genus is very 
universal, since species are recorded from almost every 
locality that has been visited by the carcinologist. 
