58 
ova are deposited on tlie external surface of tlie male parent, 
where they possess all the benefits of free exposure, with a 
sufficient portion of animal heat. The eggs of the Crab and 
Lobster possess the same advantage, chiefly perhaps for the 
sake of a frequent change of water, which is equivalent to a 
flowing stream, the health of this class of creatures mater- 
ially depending on the frequent renewal of the purest water, 
but in a less degree also, for the sake of vital heat and 
protection. They are therefore suspended to the body for 
a long period, hut are developed very quickly after they are 
shed. 
In our present state of knowledge we can only wonder at 
the variety of nature, by which it becomes the duty of the 
male Syngnathus Actis to carry about, enclosed in cells, be- 
neath the caudal portion of the body, the eggs, and after- 
wards the young; which take refuge there even after their 
first exclusion; and that too, it would seem, not only at the 
approach of danger, but for the sake of warmth and shelter. 
This curious fact displays an analogy to the Kanguroo and 
other marsupial animals, and finds a correspondence in the 
mysis, a genus of shrimps common on our coasts ; of which 
one sex, carries about under its thorax, supported by an or- 
ganization fitted to the purpose, the eggs and afterwards the 
young, until they are able to shift for themselves. 
It appears that in what, are termed viviparous fishes, no 
direct communication of nourishment take3 place between the 
parent and offspring; and the remark of Gesner, that one 
species of Shark is attached by a funis to its mother, has not 
been supported by further testimony. It follows then, that 
the quantity of nutriment originally enclosed in the egg 
(usually a yolk and white, though these are not clearly dis- 
tinguished by their colour in most marine animals) is exactly 
fitted to the duration of the creature’s faetal life, the whole 
being absorbed into the body just at the moment of birth. 
But there is reason to believe also, that in some species the 
egg increases in size after exclusion, by an endosmodic ab- 
sorption from the surrounding fluid : thus allowing room for 
a greater increase of bulk, as well as providing a more diluted 
nourishment to the embryo; and at the same time affording 
an explanation of the fact, of the disproportionate size of the 
newly excluded fish, compared with the deposited pea. 
A curious part of our subject is the frequent occurrence of 
hermaphroditism in fishes; a circumstance that displays itself 
most frequently in the presence of a melt on one side of the 
body, and a roe on the other; but I have seen an example in 
the Mackarel, where a single lobe of roe lay between the two 
usual lobes of melt. Whether fishes thus circumstanced are 
capable of self propagation has not been ascertained, and the 
