46 CTENOPHORA. 



(d) Two per-radial canals, one on each side, each of which 

 bifurcates to form the inter-radial canals (four in all), each of 

 which again bifurcates to form the ad-radial canals (eight in 

 all), which are continued orally and aborally just beneath the 

 swimming plates as the meridional canals. These canals end 

 blindly without intercommunication. 



Reproductive System. — The ctenophore is hermaphroditic 

 and ova and spermatozoa are proliferated from the walls of the 

 meridional vessels. 



A portion of a ctenophoral row should be cut off, and exam- 

 ined under a microscope, to ascertain the arrangement and rela- 

 tion of plates and cilia. 



Make a drawing of a side view. 



Make a diagram that will show the appearance of a merid- 

 ional cross-section. 



Abbott: The Morphology of Coeloplana. Zool. Jahrb., 24, 1907. 



A. Agassiz: Embryology of the Ctenophorse. Am. Acad. Arts and Sci., 10, 



1874. 

 Mayer: Ctenophores of the Atlantic Coast of North America. Carnegie 



Inst, of Washington, 1912. 

 Parker: The Movements of the Swimming-plates in Ctenophores, with 



Reference to the Theories of Ciliary Metachronism. Jour. Exp. Zool., 2, 



1905. 



