316 WM. A. KEPNER AND FRANK HELVESTINE, JR. 



4. The lining epithelium of the pharynx is sparsely nucleated 

 and relatively low. 



5. The pharynx arises after the fundament of the central 

 nervous system has made its appearance. The pharynx is 

 fully differentiated before the zooids of a dividing Microstoma 

 separate. 



6. Of the differentiating organs the central nervous system 

 maintains the most intimate connection with the parent food 

 supply throughout the development of the new zooid. 



7. Cells corresponding to 'Schliesszellen ' of Planaria appear at 

 the fundus of developing pharynx. These are transitional cells 

 between the pharyngeal and enteric epithelia. 



LITERATURE CITED 



Graff, L. von. 1909 Die Siisswasserfauna Deutschlands. IV. Turbellaria, 



Strudelwlirmer. I. Teil: Allgemeines und Rhabdocoelida. Jena. 

 Martin, C. H. 1908 The nematocysts of Turbellaria. Quart. Jour. Mic. Sc, 



vol. 52. 

 Mattiesen, Erich 1904 Ein Beitrag zur Embryologie der Siisswasserdendro- 



colen. Zeitschr. f. wiss. Zoologie. Bd. 77. 

 Parker, G. H. 1917 a Nervous sy.stem in Actinians. Jour. Exp. ZooL, vol. 22. 



1917 b The movements of tentacles in Actinians. Jour. Exp. Zool., 



vol. 22. 



