7. Anthozoa (incl. Hydrocorallia). B. Alcyonaria. 15 



network is connected by means of canals chiefly longitudinal with the canal 

 system in the axial region of the colony. In addition to the rigid axis 15- 

 20 mm long the author has found another smaller axial rod (3-5 mm) in the 

 anterior (free) extremity of the colony. The adult polyps may reach a length 

 of 75 mm when fully expanded. The external opening of the stomodseum, 

 surrounded by 8 small lobes, is a slit the long axis of which is nearly always 

 placed parallel to the long axis of the stem of the colony. The stomodseum 

 is lined by ciliated ectodermic cells and has two ciliated grooves, the ventral 

 one being more strongly developed, especially in the inner half of the stomo- 

 dseum. The epithelium of the stomodseum is continuous with the two dorsal 

 mesenterial filaments which are V-shaped in section and are ciliated. The 

 endoderm cells which cover the stomodseum and abut on the coelenteron are 

 large especially in the inner half of the stomodseum. Each of these cells 

 bears a flagellum and contains numerous spherical granules sometimes colour- 

 less and resembling fat globules, in other specimens dark yellow. The me- 

 senteries possess strong protractor and retractor muscles. Gonads are borne 

 only on the 6 ventral and lateral mesenteries and usually on the parts of 

 these mesenteries situated in the stem of the colony. All the polyps of the 

 same colony are of the same sex. An ovum is formed from an endoderm 

 cell which grows enormously, the surrounding cells dividing and forming a 

 follicle composed of elongate cells each provided with a flagellum. The endo- 

 derm cells which give rise to the male products migrate into the mesoglcea 

 of the mesentery and divide there. The sacs containing the spermatids 

 are surrounded by a layer of ciliated endoderm cells. Both these and the 

 larger ovarian follicles project from the mesentery and are attached to the 

 latter by a stalk composed of mesogloea and endoderm cells. Colonies were 

 examined from December to May but no mature males were found; spermatids 

 were present in some. In the smallest buds about 3 mm long there is a 

 mouth but no tentacles, the stomodseum is lined by cells mostly flagellated, 

 the 8 mesenteries are formed and the 2 filaments which are present resemble 

 in structure and position the dorsal filaments of adult polyps, the other 6 

 being scarcely indicated; there are no gonads. In buds 5 mm long the sto- 

 modseum is somewhat better developed and the flagellate cells are especially 

 abundant in the positions where the 2 ciliated grooves will be formed; the 

 ventral and lateral mesenterial filaments are more distinct. Tentacles appear 

 in buds 1,5 mm long, and in specimens 3 mm long pinnules are formed upon 

 the tentacles and the genital organs are recognisable. Sperm sacs are present 

 in buds only 1 mm long. There is no dimorphism in Veretillum as de- 

 scribed by Kolliker. Gland cells are abundant in the ectoderm and sometimes 

 of very large size. The oral disc is richly provided with elongate sense cells, 

 ganglion cells and myoepithelial cells. A characteristic feature of all the 

 cellular elements of F. is their richness in spherical droplets of a fatty 

 appearance; besides these there are throughout the colony large spherical glo- 

 bules which enclose similar droplets and may like the others contribute to the 

 phosphorescence. 



Hickson describes the structure, distribution and early development of Alcyo- 

 nium. For structure see Bericht f. 1895 Coel. p 9, 16. The early stages of 

 development are very variable as regards the external signs of segmentation. 

 A few hours after fertilisation there is a stage in which the embryo consists 

 of a single mass containing several protoplasmic "islands" almost free from 

 yolk, in each of which there is a nucleus. These islands increase rapidly in 

 number and soon cell outlines become differentiated. A central cavity appears 



