440 Dr. E. Haeckel on a new Foj^m of 



The most developed, largest, and oldest buds have a thick 

 disciform umbrella, rather more than 1 millim. in diameter, 

 and are quite different both from the full-grown Geryonia has- 

 tata and from the youngest larvae of that species, which also 

 had umbrellas 1 millim. in diameter. Geryonia hastata de- 

 velopes all its organs in sixes-, the buds, on the contrary, in 

 eights. During its metamorphosis Geryonia developes three 

 circles, each of six tentacles, the tentacles of each circle being 

 quite different from those of the other two. The Medusa-buds, 

 on the contrary, bear eight similar tentacles affixed in deep 

 notches of the margin of the umbrella, half on the dorsal sur- 

 face of the umbrella. Of the eight marginal lobes, which pro- 

 ject far between the notches, each bears at its apex a sensory 

 vesicle, which projects freely upon a short peduncle. In Gery- 

 onia, on the contrary, the margin of the umbrella is not divided 

 into lobes, and the twelve sensory vesicles are completely en- 

 closed within the gelatinous substance of the margin. Equally 

 important differences are presented by the gastrovascular appa- 

 ratus of the mature Geryonia and that of the buds produced in 

 its stomach. In the former the small campanulate stomach is 

 seated upon a long solid gelatinous peduncle, in the surface of 

 which six separated canals, originating from the base of the 

 stomach, ascend to the umbrella, on reaching which they are 

 bent round, and run in the subumbrella as radial canals to the 

 margin of the disk. Here the six canals are united by a circular 

 annular vessel, from which seven csecal centripetal canals are 

 given off in a radial direction inwards between each pair of 

 radial canals. In the buds, on the contrary, there is a perfectly 

 simple, rather long, cylindrical stomachal tube, which leads into 

 eight broad and flat radial sacs reaching to the base of the tenta- 

 cles. These stomachal sacs are united by an annular vessel, which 

 runs along the margin of the eight lobes. 



That the singular buds which sprout from the tongue of the 

 Geryonia within the stomachal cavity cannot themselves be 

 developed into Geryonice is perfectly evident. By no metamor- 

 phosis could this bud, which is so completely different in the 

 fundamental structure of its body, revert directly to the form of 

 the parent animal. Nor, from its whole structure, can it be 

 converted into a quadruplex Geryonide. Nothing remains, there- 

 fore, except to seek the further stages of development of the 

 buds in some other family of Medusae. There is, however, only 

 a single group of Medusae which shares the above-mentioned 

 very characteristic peculiarities of structure with the buds of 

 Geryonia. This is the family of the JEginidce, A species of this 

 family, Cunina rhododactyla, occurs in great quantities in com- 

 pany with Geryonia hastata ; indeed I have captured this Cu- 



