GILL-BARS 



423 



wards, of a tongue-like process, the secondary gill-bar or 

 septum (Fig. 107, br. sep. 2\ so that in the adult the slits 

 and intervening bars are seen to be arranged in couples, 

 the supporting rods (br. r. i) of the primary bars (br. sep. i) 

 A B 



air 



FIG. 109. Ainphio,rus lanczolatus. A, transverse section of the pharyngeal region. 

 , dorsal aorta; b. atrium; c. notochord ; <co. coelome; e. endostyle ; g. gonad 



(ovary) ; kb. branchial bars ; kd. pharynx ; /. " liver" ; my. myomere ; n. nephri- 



diu ', shown as if opening into the coelome ; r. spinal cord : sn, sn, dorsal and 



ventral spinal nerves. 

 B, transverse section of the intestinal region, atr. continuation of atrium on right 



side of intestine ; ccel. coelome ; d. ao. dorsal aorta ; int. intestine ; myom. 



myomere ; nch. notochord ; neu. spinal cord ; s. int. v. sub-intestinal vein. 

 (From Parker and Haswell's Zoology : A, from Hertwig, after Lankester and 



Boveri ; B, partly after Rolph.) 



being forked below. A further complication is produced 

 by the formation of transverse connections, supported by 

 skeletal rods, between the gill-bars. The gill-slits are more 

 numerous than the muscle-segments or myomeres (myam) t 

 and owing to their obliquity, a large number of them always 

 appear in a transverse section (Fig. 109, A). 



