44 



ZOOLOGY 



entering the pharynx, passing thence by the gill-slits into the atrium, 

 and out at the atriopore. The current, as in Tunicata and Balano- 

 glossus, is both a respiratory and a food current, the animal feeding 

 passively on the minute organisms in' the surrounding watery 



. 



FIG. 699. Amphioxus lav.ceolatus. Diagrammatic tran- ion of the pharyn- 



geal region, passing on the i _rht through a primary, on the left thr- ; lary branchial 



lamella, ao. dorsal aorta; '. >lerm ; ec endostylar portion of . t'aseia or investing 



layer of myomere ; jli . ut containing fin-ray; y. gouad ; (//. glomerulns ; /. 



iDranchial artery ; &/, pj. 'cd atrial and ctelomic wall (ligamentum denticu- 



latum); m. myomere; int. trap 10 ; />.. nephridium ; or, metapleural lymph-sp;n-o ; 



p, atrium ; sc, coalome ; si, ventral aorta ; .- nt>tochord and reuron ; uf, spaces in 



ventral wall. (From Korschelt and Heider, aft-/r liatschek.) 



Coelome. Owing to the immci 

 cavity, which is a true coslome, is much re< i 

 in the pharyngeal region, by paired cavitit 

 A, co., Fig. 699, sc.) lying one on either sid 



trium the body 



is represent^ 1 . 



'., Fig. 69 7, 



don of 



