48 • EilBEYOLOGTCAL MOXOGllAPHS. 



2C. The oldest stage raised artificially ; near the end of Octolier. Six of the calcareous septa o\erto]) the other 

  six, and a new series of 12 additional septa is faintly indicated; the colnmella {coll.) is already formed. 

 This individual is distinguished by a very considerable development of the epitheca. J. 



27. A much further developed stage, nearly 2 mm. high. There are 24 septa which fall into three orders 



according to their relative sizes. The epitheca is not visible, as it does not reach to the margin of the 

 cup. I. 



28. Almost fully developed single individual with 48 septa, 12 of which overtop the others. 



Subse(iucntly 48 new septa, alternating with those already formed, make their appearance, and the main 

 septa are at the same time increased in number fioni 12 to 24. 



29-42. CoralUuin rubruni. From Lacaze-Duthiers, Histoire naturelle du Corail, etc. Paris: 1864. I'ls. I., II., 



XL, XIV., XV., XVII-XIX. 



29. One of the many forms assumed by the ciliate larva in its natural position, with the mouth-end downwards. 



30. Another, more worm-like form of the ciliated larva (com])are corresponding stage of Astroides, fig. 1). 



31. One of the stages of transformation from the worm-like to the disk-like form. The aboral region becomes 



enlarged, and the oral end sinks in. 



32. An expanded " oiizoite " (animal developed from an crjcj) attached to a rock ; the latter not reproduced here. 



33. An oozoite still older than the preceding, though still simple. Expanded and seen from the oral side. 



34. The same oozoite seen in fig. 32, but in a contracted condition. 



35. One of the tentacular arms of the adult, seen in proHle. In this position the barbules are seen to he directed 



ohli(|uely from above downward, and from within outward. 



36. Oral view of a larva several days after its metamorphosis. The central part around the mcnith (i) is already 



elevated and forms a bourrclct ; the base is not so regularly circular as it was at first, since it conunences 

 to spread itself over the body to which it is attached. 



37. Extremity of a barbule from a tentacle of an adult, magnified 250 diam. cc. External cell-layer, en. Large 



cells forming a network and bearing vibratile cilia. 



38. Spicules which are exposed on tearing away the epidermis from the adult. 



39. Nematocysts from the adult; one with the mother-cell still suri'ounding the nematocyst — or internal cap- 



sule — witli its spiral tilanient. 



40. Portion of a radial fold (mesentery, m ill) bearing (1) at m. an egg, the capsule (cap.) of which has in part 



fallen away, and the vitellus (fit.) of which jiresents a very distinct clear spot {nV), corresponding to the 

 transparent (gerininative) vesicle, in the middle of which are to be seen the germiuative sjiots (nil.); (2) at 

 te. a capsule in process of development, reniarkalile on account of an apparently empty space (X) surrounded 

 by a cellular band (k) which lines tlie capsule ; this is a testicle. 



41. A small rock to which are attached three zoanthodemes, the polyps of 2 and 3 having been destroyed. 



3. The beginning of the corallum ; a plate with irregular sides covered here and there with small project- 

 ing corpuscles bristling with iioints. 2. Exhibits an early form of the corallum. It consists of an irregu- 

 lar plate, curved into the shape of a horse-shoe, formed of masses of agglomerated .spicules. The general 

 cavity of the body of the polyp occupies the interior of this curve, and consequently the .solid plate is 

 formed, as may be seen at 1, in the midst of the sarcosoma between the external and the internal surfaces. 



42. Zoauthodenie composed of one oozoite (1), and three " blastozoites " (budded individuals), 2, 3, 4. 



43. 44, 46. Goryonia verrucosa. From G. von Koch, Vorlaufige Mittheilungen iiber die Oorgonien (Aleyouaria 



axifera) von Neapel und iiber die Entwicklung von Gorgonia vei-ruoosa. Mittheiluugen aus dcr Zoolo- 

 gischeu Station zu Neapel, Bd. III. 1882. Figs. 10, 13, 15. 



43. Section through an egg bef(jre the segmentation spheres have been differentiated into distinct layers. The 



outer cells are somewhat smaller than the inner, and all possess distinct nuclei. The latter ajipear to be 

 wanting in some of the cells simply because lying outside the plane of section. 



44. Longitudinal section' of an attached individual, showing the thiu layer of ectoderm infolded to foini the 



jdiaryugeal sac which opens into the entodermic cavity below. 



45. Note. — Figures 45 and 16 have been accidentally transposed by the lithographer. For explanation of 45 



see above. 

 16. Gonjonia verrucosa. From A. 0. Kowalevsky, Observations on the development of the Cadentrata (cited 

 above). Taf. V. fig. 19. Ciliated larva. There are to be distinguished two layers in the entoderm. The 

 peripheral layer (en.) is striate, indicating its composition out of cylindrical cells, with irregularly arranged 

 nuclei ; this merges into the iniier layer (en'.) which is granular, filled with highly refractive spherules, and 

 is ciliate. (The cilia are not figured by the author.) The latter is considered equivalent to the yolk-mass 

 of Alcyouium and of Astraja. 



46. Four cells of the ectoderm, one of which has migrated into the imderlying mesodermic layer {Zu-isclicn.iuh- 



slanz) and shows at one side of its nucleus the cross section of a spiculum which is being formed within it. 

 The same cell somewhat nuire enlarged is figured near by. 



