PBYLUM 



growth takes phi 



the i ^ c 



aperture, fon in 



..nqglossus (p. 3. 

 tongue which extends 

 downwards, dividing the 

 original cleft into two, 

 itself becoming a 

 ndary lamella. A 

 further complication is 

 product M! by tl 

 i nation of tra 



or 



supported 



by rods connecting the 



primary septa with one 



.r.her at tolerably 



vals. 



The Atrium. The 

 gill-clefts lend into a 

 wide chamber occupy - 

 'ing most of the sp 

 'ween the body- wall 

 the pharynx, and 

 ! od the ai ; gs. 



74-2, B, and 7- 

 It is crescentic in 

 tion, surrounding the 

 : iral and lateral 

 ns of tl 



but not ils dorsal por- 

 tion. It ends blindly 

 in front; o] - m- 



Ly, behind the level 

 of the pharynx, by the 

 and 



is continued backwards 

 by a blind, pouch-like 

 extension Wp) lying to 



e right of tl 



tine (Fig. 742, I>, atr.\ 



The whole (tavity is 



od by an a trial epi- 



thelium of .--<.>''-Tmal 



As in Ascidia, 



V cilia lining tl: gill- 



.. II 



