lUMKIM A I.MCIHA SP. X. 17 



to tlio niiiutli. h1io\vIii<;' a \vf>ll-m;u-kp(l iniiei- opitliftlimii (I'.ep.) fovevin^' 

 a mass of vacuolated eiifloderm cells (p. r. r.) 



Pig. 11. — X 300. Horizontal section of eudoderm of liydvanth imme- 

 diately below the endoderm projections (e. pr.). There is a tendency for 

 the formation of n definite inner e]iithplinm of gland-cells on four tre- 

 foil-shaped endoderm ridges. 



Fig. 12. — x 300. Horizontal section of endodei-m near base of 

 hydi'anth in which the cells are mostly vacnolnted : gland-cells (cep.) 

 are few, and scattered at the periphery. 



Fig. 13. — x 300. Transverse section of hydrorhi/a, showing the thin 

 perisarc floor (/.) in contact with sea-weed (s.-ir.) and a vertical, sup- 

 porting pillar iji.}. 



Fig. 14.— x 300. View fi-om above of a piece of hydrorhiza. showing 

 vertical pillars (p.) on each side. 



Fig. ir>. — X 300. Internal view of piece of hydi-orhiza with one side 

 removed, showing three vertical pillars (]>.). thin floor (/.). and thick 

 roof (r.). 



Fig. It!, x <>0(>. Tentacleof hydranth in transverse section, showing 

 soft upper perisarc {i^.py.f.), endoderm axis (f'i^), especially muscular 

 ectoderm {m.p. t.) and thick, firm, lower peri.sarc (f.pr.). 



Fig. 17. — X 000. Piece of tentacle in longitudinal, vei-tical section, 

 showing septate endoderm axis (.s. e. f.). 



Fig. is.— X BOO. Piece of tentacle in longitudinal, vertical section, 

 showing non-septate endoderm axis (». .s p. t.) ; diatomsand other debris 

 {(I.) are atta,ched to the lower, thick, firui perisarc. 



Fig. 19. — x HOO. Distal end of tentacle in horizontal section, show- 

 ing nematocysts (».) in the naked capitulum. 



Fig. 20. — x 300. Horizontalsectionthrough whole length of tentacle, 

 showing its origin from the hydranth and the perisarc covering. 



Fig. 21. — x 180. Section of young gonophore being budded from 

 hydrorhiza. 



Fig. 22. — x 180. Section of a somewhat older gonophore, showing 

 the first sign of genital cells ((j.). 



Fig. 23. — x 300. Section of a small piece of the gonophore, showing 

 a group of genital cells {q.) in the ectoderm. 



Fig. 24. — X 180. An older gonophore in vertical, median section, 

 showing the beginning of the endoderm diverticula {p.d.) and the ecto- 

 derm cai^cells {d.p.) resembling the '■ Deckenplatte " of the Calypto- 

 blastica. 



Fig. 25. — X 180. Vertical, median section of adult gonophore. with 

 endodei'm diverticula {e.d.) meeting clumps of elongated ectoderm cells 

 VOL, 4, r.\RT 1. 2 



