TUBULAlilA SOLITAKIA. 95 



Fig. 9. — x 125. — Cross section of female gonopLore ; it shows the 

 absence of distinct radial canals in the endoderm of the nmln-ella wall. 



Fig. 10. — X 75. Cross section towards the basal end of hydrocaulus 

 to show the endodermal canal system. The vesicular endoderm, occupy- 

 ing a considerable portion of the cavity, contains large nematocysts 

 {I. n.). 



Fig. 11. — X 5<>. Cross section of hypostome region to show the 

 tentacular and endodermal ridges. 



Fig. 12. — X 50. Cross section tlu-ough the base of polyp showing : 

 (1) Central channel lined by an irregular epithelium : (2) vesicular 

 endoderm ; (3) the origin of the basal or proximal tentacles. 



Fig. 13. — X 100. Cross section through the region of the perisarc- 

 secreting groove. It shows (1) expanded endodermal canals (e. c.) with 

 vertical radial septa (v. s.) ; (2) horizontal section through the endo- 

 dei-mal epithelium {eel.) hanging down from the diaphragm ; (3) the tall 

 glandular epithelium secreting the perisarc. 



Fig. IJ;. — X 200. Small piece of cross section just below the region 

 of the perisarc-secreting groove. In this specimen the ectoderm is 

 charged with large granular masses of deeply-staining substance, similar 

 in appearance to the masses marked^r. in the basal epithelium (Fig. 5a), 

 pi\ Fig. 5, and g. m., Fig. 13. Such masses are by no means invariably 

 found in the ectoderm below the perisarc groove. 



Fig. 15. — X 200. Small portion of Fig. 10 to show endodermal 

 canals. 



Fig. 16. — x 200. — Cross section through the tuber-like outgrowth 

 from hydrorhiza, as it lies in situ in the sponge. The modified tissue 

 of sponge contiguous with the hydroid is also shown (sp.). The tall 

 endoderm cells are crowded with globules. 



Fig. 17. — x 50. Gonophore with enclosed actinula and shrivelled 

 manubrium. 



Fig. 18. — X 75. Peduncle cai-rying terminally an abortive gonophore 

 and laterally an ordinary fertile gonophore. 



Fig. 19. — x 200. Apical portion of gonopliore showing the opening 

 of the uml>rella to the exterior. 



Fig. 20. — x 150. Longitudinal section of gonophore with the ova 

 being al>sorbed into an egg-mass (g. e. vi.). The first segmentation 

 nucleus has not been identified with certainty. 



Fig. 21. — x 500. The beginning of the formation of the egg-mass. 

 It is suggested that sn, and s)u may 1:)e fertilised nuclei. 



Fig. 22. — x 150. Longitudinal section of gonophore occupied by 

 embryo surrounded by egg-membrane (e. m.), and possessing several 

 nuclei, one of which is in a state of division (dy.). 



