CAPRELLA. 51 



derable time, and then suddenly stop, remaining perfectly 

 motionless, not even moving their antennas." 



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 jEgina. 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. 



