52 



HISTOKY OF CRUSTACEA. 



Chap. VII. 



antennal scale of the Prawns,^ 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 setae 

 at its hinder margin. The Zoese of the Crabs usually 



Figs. 19—23.8 



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. 



^ In a memoir on the metamorphoses of the Porcellame I have errone- 

 ously described this appendage as the " flagelkim." 



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

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



