1. In many particulars this work is a confirmation of the previous paper by Hargitt, especially in regard to the several nuclei in the unsegmented egg, the irregular shape of many such nuclei, and the irregular phases of cleavage. 2. The ova arise in any region of the polyp, which is contrary to Bunting's statements. The young ova gradually increase in size, during which time the nucleolus becomes vacuolated and the cytoplasm is occupied by numerous microsomes which become transformed into spherules. The cytoplasm changes its staining reaction during this time. 3. The chromatin during the growth of the egg stains less intensely than when in the younger state. Much of the chromatin migrates into the cytoplasm and is surrounded by vacuoles. The highly vacuolated condition of the cytoplasm is probably directly due to this migrating chromatin. The size of the nucleus decreases greatly. 4. In Hydractinia there were found three distinct kinds of granules, yolk masses, coarse granules and small bodies around the periphery. The small granules are distributed exclusively to the ectoderms. 5. Maturation begins in Hydractinia before the eggs are deposited. The process is by the formation of a distinct mitotic figure. It is very rare to find a polar body attached to the deposited egg. 6. The female pro-nucleus is very much smaller than the egg nucleus before maturation but it persists as a definite structure until cleavage begins. It is not at any time indistinguishable. The male pro-nucleus moves through the cytoplasm until it approaches the female pro-nucleus when the two fuse and fertilization is effected. 7. The first, and all subsequent cleavages, is by the mitotic process. A definite segmentation cavity is formed in the two-celled stage which increases ih size. This cavity is gradually filled with cells until the planula is a solid mass of cells. 8. The false membrane in Pennaria is a transitory structure and probably of a fluid nature. Later its place is taken by a true membrane. 9. Maturation in Pennaria begins before the eggs leave the medusa. The polar bodies are ephemeral in character and rarely found attached to the deposited egg. The polar bodies are formed by the mitotic process. 10. After the two polar bodies are formed in Pennaria there is a distinct migration of a considerable amount of chromatin into the cytoplasm. The chromatin is transformed into vesicles which eventually are taken up by the cytoplasm. Sometimes these vesicles contain chromatin and persist for some time and may (?) divide mitotically, giving rise to a pseudosegmentation. 11. The spermatozoa may penetrate the egg before it is laid. The sperm head is transformed into a male pro-nucleus which moves through the cytoplasm toward the animal pole to unite with the female pro-nucleus. 12. Cleavage in Pennaria is at all times by the mitotic process. The chromosomes become transformed into vesicles during the late anaphase and early telophase. The vesicles may or may not unite into a definite "resting nucleus" before the next cleavage. 13. During cleavage in Pennaria there is a distinct centrosphere which contains granules with centrosome powers. This centrosphere is more conspicuous in Pennaria than in Hydractinia. The new prophase spindle arises within the old centrosphere. 14. Papillæ are found in both Hydractinia and Pennaria before segmentation, much as described by Hargitt. 15. A partial condition of fragmentation is seen in the migration of chromatin into the cytoplasm in both species. 16. No clear evidence of amitosis was observed. 17. Inclusions are frequently found in the egg of Pennaria.