Davenport. — Eudditi'); in Brvczoa. 



PLATE III. 



ABBREVIATIONS. 

 An. Anal side of polypide. l-m])'drm. Kamptoderm. 



All figures from preparations of Paludicella Ehrenbergii. 



Figs. 21-25. Longitudinal sections through buds of polypides at successively older 

 stages. The tip of the colony, and therefore the anal aspect of the 

 polypide, is to the right in all cases. All figures X 410. 



Fig. 21. Stage of Figure 37 (Plate IV.). Few nuclei in central region. 



Fig. 22. Shows rapid growth of bud, chiefly at neck of polypide. The two inner 

 cell layers are about to separate to form the common cavity of atrium 

 and oesophagus. 



Fig 23. Beginning of formation of alimentary tract at rectum, rt. The row of 

 nuclei separating the atrioccsophageal cavity from the alimentary tract 

 is due to the fusion of the two inner ]a3'ers of the bud along this line. 



Fig. 24. Rectum and stomach completed. Retractor muscles begin to form. 



Fig. 25. Lophophore and young tentacles have made their appearance, and 

 oesophngus and pharynx are separated from atrium. Beginning of 

 formation of brain at gn. 



Fig. 2G. Part of cross section of a branch of stage of Figure 30. Parietal mus- 

 cles, mu. par., occupy a diameter of the section, and are attached to 

 the cuticula. X 63.5. 



Fig. 27. Young parietal muscle at stage of Figure 28. This is one of the pair 

 which in a later stage are foimd lying together in Figure 26. X 635. 



Fig. 28. Cross section of branch showing young polypide, and reticulated vacuo- 

 lated cells. X 410. 



Fig. 29. Bit of body wall, with cuticula separated from underlying ectoderm to 

 show ends of parietal muscles. X 6!)0. 



