S . 
454 _ Bibliography. 
“Certain facts admit of no dispute; such as the existence of a vig- 
orous hydra attached to. a solid substance, with long flowing silky ten- 
tacula ; an alteration in the figure of the body, or the formation of an 
embryonic roll of Medusze on the disc ; the gradual maturity of each 
Medusa and its liberation from the roll; the disappearance of the orig- 
inal tentacula of the hydra; the emerging of a new circle of tentacula 
from a smooth fleshy bulb, sustaining the embryonic roll, as the former 
are obliterated, and as the Medusce “approach maturity ; the evolution 
of this fleshy bulb as a pp _— along with their departure, 
which becomes the parent of eny by eg ee and its perma- 
mence-as.an independent animal. cS ie 122-3 
* All the eer, in the embryonic roll are separate and distinct 
euivenie. Each is in close application to that which is next below, if 
itself be appetdacet or lies between two if intermediate. The probos- 
cis is outermost if the indiyidial be uppermost in the roll ; thussall lie 
in the same direction, the proboscis outermost, as the Medusa escapes, 
from the next left behind. When the last remains in adhesion to the 
y bulb, its proboscis projects outwards also. Thus the under sur- 
rae the oeabrysi is always outwards, while a portion of the roll.” 
24.) 
q “ bien by repeated long, and painful observation, I have: en- 
deavored to. — the history of the Hydra tuba and the Meduse ori- 
- ginating from it, my purpose has been but Pp tc gb I hav 
selected many individuals, and [ have chosen colonies of both, to dis 
cover whatever changes they should undergo. The hh ded grew, it fed, 
red, its existence was long.’ The Medusa lived, it neither fed nor 
bred, its cet was infinitely shorter; nor did it undergo the small- 
est change from the first moment of aes for: fifty-five days. Its 
life could not be peverncsed: on any occasion, beyond sixty days. Be- 
tween the form and “habits of these two adele there is not the small- 
™ pis sur les Animaux Fossi pe Konincx. Liége, 
1847. hie des genres. Productus et 
(Ann. and ae Nat. Hist., 
of a series of 5 
through many periodicals, memoirs and trans- 
he first ret? rt contains a list of 107 works and 
ve, 3 
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5: 
Comal 
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, witha classiicetcat « the species. . detailed description 
ch 
of rng species is given, to which is appended a very complete . . 
my. From the geological and geographical distribalion sit Tou 
wee st a few notes. he number of species of Produc ibed 
am 62, of which 4 are Devonian, 47 Carboniferouljaa Permian, 
and 1 ssic. Of the 47 Carboniferous species, 35 ae found in 
ps lower divisions. 
