THE PHARYNGOBEANCHII. 



11< 



are attached to a hoop of the same texture placed around 

 the margins of the mouth (Fig. 29,/, g). These probably 

 represent the labial cartilages of other fishes. The oral 

 aperture leads into a large and dilated pharynx, the walls 

 of which are perforated by numerous clefts, and richly 

 ciliated, so that it resembles the pharjmx of an Ascidian 

 (Fig. 28, B, /, g). This great pharynx is connected with 

 a simple gastric cavity which passes into a straight intes- 



Fie. 28. 



Fig. 28. — Amphioxus lanceolatus. — «, mouth ; b, pharyngobranchial 

 chamber; c, anus; rl, liver; e, abdominal pore.— B, the head en- 

 larged : a, the notochord ; b, the representatives of neural spines, 

 or fin-rays; c, the jointed oral ring; f/, the filamentary appendages 

 of the mouth ; e, the ciliated lobes of the pharynx ; /, (/, part of the 

 branchial sac ; /(, the spinal cord. 



tine, ending in the anal aperture, which is situated at the 

 root of the tail at a little to the left of the median line 

 (Fig. 28, A, c). The mucous membrane of the intestine is 

 ciliated. 



An aperture called the abdominal pore (Fig. 28, A, e), 

 placed in front of the anus, leads into a relatively spacious 



