334 



MANUAL OF ELEMENTARY ZOOLOGY 



front end of the pharynx two peripharyngeal bands of long 

 cilia connect the endostyle with the epibranchial groove. By 

 the cilia of the gill bars and peripharyngeal bands the mucus 

 is passed upwards to the epibranchial groove, which carries 

 it backwards to the oesophagus. As it goes, it entangles 



Fig. 242. — Nephridia of Amphioxus. — After Boveri. 



A lateral view of the upper region of the pharynx, the body-wall being removed. 

 The atrial chamber is laid completely open by the removal of its outer wall, 

 which is cut through along its line of insertion. The result is to show that 

 the chamber is prolonged dorsally into a series of bays (£.), which lie 

 outside the tongue bars (t.b.). Into these bays the nephridia («.) open by 

 pores {p.), while they also 1 project internally by blind funnels (/), fringed 

 by very large solenocytes (c.). > The bays are separated by ridges ui), formed 

 by a downgrowth of the walls of the ccelom over the primary bars (/.£.) ; 

 mym., a myomere; jy., one of the synapticula? connecting the pharyngeal 

 bars. 



small organisms brought in with the water at the mouth, 

 and carries them backwards to be digested. Each primary 

 bar contains a narrow coelomic canal. At the tops of the 

 bars the ccelomic canals join a longitudinal canal, known 

 as the dorsal ccelom, which lies within the body-wall above 

 the atrium. Below the bars the canals join a longitudinal 

 subendostylar ccelom. This arrangement is the remains of 



