156 SIDNEY F. HARMER. 



PLATE 10. 



Fig. 23 was drawn with Zeiss DD, and was not afterwards reduced. Tlie 

 other figures were reduced two thirds after being drawn. Figs. 24 and 25 

 were drawn with DD ; Figs. 26—28 with F ; Figs. 30—32 with A; Fig. 33 

 with A, the front lens of which was removed. Fig. 29 was not drawn with a 

 camera lucida. 



Fig. 23. — T. plumosa. Polypide-bud, partly diagrammatic; for compari- 

 son with the ovicells shown in Figs. 22, 25, &c. s. m. Somatic mesoderm, 

 reflected on to the very thin tentacle-sheath, which becomes continuous witli 

 the tentacles near their proximal end. The epithelium of the stomach (below 

 the tentacles) is derived from the inner layer of the bud, and is covered by 

 the outer layer. The distinction between the two layers is not easily made 

 out in the mass marked " tentacle." 



Fig. 24. — T. plumosa. The embryophore is in stage D, and the distal 

 part of the ovicell is in stage E. Numerous excretory vesicles occur distally. 

 A B = 460 ^, C B = 110 /i, D E = 275 fi. 



Fig. 25. — T. phalangea. Advanced stage E. The growing edge is much 

 lobed and thickened on the left side of tiie figure. The vestibule is much 

 shortened; it is separated by the space y (cf. Figs. 20 and 22, and p. 148) 

 from the brown body, which is now almost free in the cavity of the embryo- 

 phore. The outer wall of the embryophore is reflected over the wall of the 

 space y (cf. the polypide-bud. Fig. 23). The embryo has greatly enlarged, 

 and three giant-cells are shown. C B = 360 /tt, F G = 385 fi ; greatest 

 length of embryo = 80 fi. 



Fig. 26. — T. plumosa. Tentacle, fresh, with homogeneous excretory 

 vesicles and pigment granules (p.). 



Fig. 27. — T. plumosa. Another tentacle belonging to the same polypide, 

 after the addition of iodine in potassic iodide. The contents of the homo- 

 geneous vesicles have been precipitated. 



Fig. 28. — T. phalangea. Tentacle, fresh, with compound vesicles and 

 pigment granules (p.). 



Fig. 29. — T. plumosa. Orifices of living zooecia. The terminal mem- 

 brane has been somewhat retracted. 



Fig. 30. — T. plumosa. Not decalcified (see p. 136). View of a colony 

 from below, after the basal lamina has been scraped away. X and Y are zooecia, 

 which are similarly marked in Fig. 31. G is the thickened edge of the 

 growing margin of the ovicell (in stage E), and corresponds with G in Fig. 31. 

 The embryophore (in stage D) lies in the proximal undilated part of the 

 ovicell. The fertile brown body, the embryo, the beginning of the nutritive 

 tissue, and the distal thickening of the investment of the brown body, can be 

 made out. A B = 900 /x. 



