52 



HISTORY OF CRUSTACEA. 



CHAP. VII. 



antennal scale of the Prawns, 5 and the first rudiment of 

 the future flagellum is often already recognisable. Of 

 natatory feet (afterwards maxillipeds) only two pairs 

 are present ; the third (not, as Spence Bate thinks, the 

 first) is entirely wanting, or, like the five following 

 pairs of feet, present only as a minute bud. The tail, 

 of very variable form, always bears three pairs of setse 

 at its hinder margin. The Zoe'se of the Crabs usually 



Figs. 1923. 6 



maintain themselves in the water in such a manner 

 that the dorsal spine stands upwards, the abdomen is 

 bent forwards, the inner branch of the natatory feet is 

 directed forwards, and the outer one outwards and 

 upwards. 



5 In a memoir on the metamorphoses of the Porcellanae I have errone- 

 ously described this appendage as the " flagellum." 



6 Tails of the Zoese of various Crabs. Fig. 19. Pinnotheres. Fig. 20. 

 Sesarma. Fig. 21. Xantho. Figs. 22 and 23 of unknown origin. 



