PLATE XIII. 



Fig. 13. — A section which follows the preceding in consecutive order, repre- 

 senting a portion of the same septum (sep.) and of the same 

 polypide bud (j)d. bd. 2). There are shown besides a portion of 

 another bud (pd. bd. 1) and numerous large ova constituting an 

 ovary (ovy. ) . ' (300 



Fig. 14. — A section following the preceding in consecutive order, showing a 

 portion of the septum (stp.), and in the cavity of the branch a 

 huge ovum (or.) in close proximity to a polypide bud (pd. id.). 

 X 600 



Fig. 15. — Section through the tip of a female colony, representing a part of 

 an ovary (ovy.), a U-n cells of a young bud (pd. bd. 2) and a 

 portion of an older bud (pil. bd. 1) to the proximal extremity 

 of which a large ovum is attached (ov.). X 600 



Fig. 16 — Section through the tip of another colony, showing two ova in the 

 germinal epithelium of the anterior edge I »r.), a polypide bud 

 (pd. bd.) with an ovum attached to its proximal extremity. In 

 the next older zooecium is an adult polypide (pd. 2) with a 

 small embryo (end).) attached to the csecal end of the stomach, 

 and in the succeeding zoceeium is a still older adult polypide 

 (pd. 1). ■ 600 



Fig. 17. — Section through the tip of a female colony showing two ova (ov.), 

 which are attached by long processes to the interior the branch. 

 These have formed no union with a bud and would have degen- 

 erated. 600 



Fig. 18. — Decalcified internode of Crista eburnea, containing an ovicell 

 (ovl.) in an early stage of development. At the proximal 

 extremity is the articulation (art.), by which the internode is 

 connected with the branch. Arising from the articulation arc- 

 two zoceeia (pd. l and pd. %), while the ovicell takes the place 

 of the third zoceeium. At the distal extremity of the branch, 

 two or three buds are forming (pd. bd.). The ovicell contains 

 a young embryo (emb.), and a tentacle sheath (tent.). 



Fig. 19. — Section of a young ovicell, containing an embrye in the two-cell 

 Btage. This figure contains but one blastomere (Id.), not yet 

 surrounded by the cells of the polypide bud (pd. bd.). ' 600 



Fig. 20. — Section immediately following Fig. 19, showing the second blasto- 

 mere i /./.I of the embryo, a portion of the elongated cells of 

 the polypide bud (pd. bd.), and the beginning of the vestibule 

 (vest.) 600 



