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THE HYDROID MEDUSAE. 
By the REV. THOMAS HINCKS, B.A., F.R.S. 
[PLATE LXXXVIII.] 
T HE title which I have given to this paper is not as strictly 
accurate as I could have desired, hut it is the best that 
occurs to me. It is my purpose to sketch the history of those 
exquisite medusiform organisms, which, long regarded as inde- 
pendent animals, are now known to be the wandering repro- 
ductive buds of the hydroid zoophytes.* To style them 
Medusae, however, is to run the risk of suggesting the idea of 
absolute individuality, and so concealing their true zoological 
significance. They are the floating flowers, so to speak, of the 
plant-like animal, detached from the parent structure at a 
certain point of their development, but still a mere term in 
a single life-series ; elements of a perfect being, but not them- 
selves complete existences, and only comprehensible when 
referred to the whole of which they form a part. The title 
must be accepted with this explanation. 
Other medusan forms, identical in structure with those to 
which I have just referred, but which have not yet been traced 
to any fixed hydroid stock, also come within the scope of the 
present paper. These are very numerous, and offer a wide 
field of interesting research to the naturalist. It is remarkable 
that in the case of so many species the reproductive bodies only 
should be known, while the plant-like colonies that gave them 
birth elude our search. Of the forty or fifty forms described 
by Edward Forbes in his classical Monograph on the 66 British 
Naked-eye Medusae,” f but few have yet been traced to their 
origin. Of the North American species, so admirably described 
and figured by Alexander Agassiz, many of which are wonder- 
fully beautiful, the same remark holds good. We know a 
large proportion of them merely as ocean-wanderers, scatter- 
ing the seed of new generations, beautiful and ephemeral, like 
* Allman has given them the expressive name of “ pi an oblasts ” — 
11 wandering buds.” 
t Published in 1848. 
z 
TOL. XI.— NO. XLV. 
