AMPHIOXUS. 



299 



resembles the pharynx Fig. 213.— View of Amphioxus from 



of Ascidia. Its internal 

 walls are mostly ciliated. 

 The endostyle extends 

 along the median ven- 

 tral line, joined by 

 peripharyngeal bands to 

 a median dorsal epi- 

 branchial groove. The 

 lateral walls of the 

 pharynx are perforated 

 by a great number of Dorsal Fin 

 pharyngeal clefts which skeleton, 

 run diagonally back- 

 wards as long slits. Dorsal 



These pharyngeal clefts 

 are twice as numerous 

 as those of the larva, Notochord 

 each of the latter be- 

 coming divided longi- o 



tudinally into two by 

 a long tongue-bar of the 

 pharyngeal wall growing 

 downwards from above. 

 The same method 

 of feeding as in Ascidia 

 is adopted. The water 

 and food - particles are 

 brought into the phar- 

 ynx, and the latter are 

 entangled in strands of 

 mucus which are even- 

 tually carried into the 

 intestine at the hind 

 end. The water is 

 driven through the 

 pharyngeal clefts into 

 the atrium, a spacious 

 cavity which, as in 

 Ascidia^ surrounds the 

 pharynx. In Amphioxus^ 



THE Right Side. {Ad nat.) 



Oral Cirri. 



Dorsal Fin 



Intestine. 



Anus. 



