282 R. T. GUNTHER, 
of the manubrium as in a normally developed bud, and so 
likewise the exumbrella ectoderm is continuous with the 
manubrial ectoderm. But the ectoderm covering the sub- 
umbrella has undergone rupture at the point a, and the entire 
bud has forced its way through the aperture. 
The future of these monstrosities must remain a matter of 
doubt. It would be interesting to know whether such abnor- 
mal buds are reabsorbed by the parent or whether they are 
capable of further growth and are then cast off. In any case 
it would seem improbable that a Medusa bud in this condition 
should eventually right itself, in spite of the acknowledged 
powers of regeneration which are characteristic of the 
Hydrozoa. 
Bud-formation of Limnocnida contrasted with the 
same process in other Hydrozoa. 
If we compare the process of development of Medusa buds in 
Limnocnida, as detailed above, -with the same process in 
other Hydrozoa, several striking points of difference are 
noticeable. In the first place the method of invagination of the 
ectoderm to form the entocodon or “glockenkern ” in Limno- 
cnida differs from the method of formation in most other 
Medusz in which the process has been described, and I am in- 
clined to think that in this respect Limnocnida exhibits a 
more primitive condition. 
As a general rule we find that in the Craspedota the earlier 
stages of the development of the Medusa buds, whether they 
subsequently give rise to free Meduse or whether they grow 
into any of the various degenerate modifications of the Medusa, 
show considerable shortening of their ontogeny. It would be 
superfluous to recapitulate all the arguments used in favour of 
this view. Weismann in his monograph on the ‘ Entstehung 
der Sexualzellen bei den Hydromedusen’ has brought forward 
abundant evidence to indicate the phylogenetic stages by 
which the primitive method of the formation of the Medusa- 
bell by the outgrowth of a circular fold has become changed 
into a process of invagination, 
