Galloway. — Dero vaga. 



PLATE 4. 



Fig. 18. Cross section of the pharynx of a mature worm. X 312. 



Figs. 19-24. Posterior face of cross sections from a single series through a bud- 

 zone in which separation is imminent. X 312. The higher the num- 

 ber, the farther forward the section is in the series. Figures 19-21 

 belong entirely to the posterior zooid. Figures 22-24 show parts of both 

 zooids. Sections 10 /x thick. 



Fig. 19. Section through pharynx of posterior zooid; dorsal lumen conspicuous. 



Fig. 20. Next section in front of that of Figure 19 showing anterior portion of dor- 

 sal pharyngeal lumen. 



Fig. 21. Same series, two sections anterior to the preceding. 



Fig. 22. Section (3rd in front of that of Figure 21) passing through ectodermal 

 invagination (sh/.) between the zooids. The entodermal wall of pavilion 

 (en'drm.) is seen below the gut. 



Fig. 23. The section immediately in front of the last, showing that on the left side 

 the plane of section is farther cephalad than on the right side. 



