130 ZOOPHYTES. 



XIV. The fleshy bulb refines into a perfect symmetrical hydra, as 

 the embryonic roll which it sustained is dissipated, and successive genera- 

 tions of progeny descend by gemmation from its side. 



Plate XVIII. Medusa bifida. 



Fig. 1. Colony of Medusae swimming at large. 



2. Specimen enlarged ; supposed proboscis from the under 



surface, a ; cloven lobes or arms, h. 



3. Specimen reversed ; orifice of the mouth, a ; arms, h. 



4. Surface, shewing four external organs around the pro- 



boscis. 



5. Another view of these organs. 



6. Lobe or arm, shewing the cone in the cleft, surmounted 



by a compound black speck, magnified. 



7. Granulated aspect of the under surface of a specimen. 



8. Granulated aspect of the upper surface. 



9. Hydra, a, with a rouleau or pendulous formation, h, seen as 



laying in a watch-glass, having fallen from its position. 



10. The same enlarged, hydra, a ; pendulous formation, b, 



being immature Medusae. 



11. Hydra pendent from the side of a jar, a, with a similar 



pendulous flexible formation, b ; consisting of imma- 

 ture Medusae. 



1 2. Another hydra, a, become shapeless hke the two pre- 



ceding, with a similar formation, pendulous from the 

 disc, b. 



13. The pendulous formation with Medusae developing, a, b ; 



detached along with a slice of the base or disc, c, as 

 now laying in a watch-glass. 



14. The same enlarged. 



15. Ultimate appearance of the same subject ; tenth Me- 



dusa, a, struggling for liberation ; eleventh, b, died ; 

 spurs or originating tentacula, d ; the latter long and 

 silky in three weeks. 



16. Portion separating naturally or accidentally from fig. 12, 



proving two or more Medusae united. 



17. The same, enlarged ; proboscis, a ; arms, b. 



The figures 1, 9, 12, 16, nearly of the natural size : the 

 rest enlarged. 



