38 CCELENTERATA. 



called an auricle. Each ctenophore then possesses four auricles, 

 which are somewhat covered over by the loose edges of the 

 terminal lobes. The fringe of cilia which borders each auricle 

 is continuous with a fringe which extends up and down the 

 inner, lateral edge of each terminal lobe. Do you understand 

 how the animal gets its food? 



Digestive System. With a pipet inject a solution of carmine 

 into the mouth opening. 



1. You can then more plainly see the long ribbon-like esoph- 

 agus, which leads to a very small stomach just beneath the 

 sensory body. 



2. From the stomach are given off the canals, which in a 

 successful injection will be seen to be as follows : 



(a) Two short "excretory canals" opening into the pit where 

 the sensory body is located. 



(6) Two esophageal canals, one on each side, passing down 

 along the esophagus. 



(c) Two tentacular canals, one on each side, passing to the 

 tentacular structure of that side. 



(d) Four meridional canals, each of which bifurcates. The 

 eight thus formed pass down the animal superficially, just beneath 

 the ctenophoral rows. 



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 Ctenephores, with 



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



1905. 



