3 2 2 
FISHES. 
and a pipe-fish ( Solenostoma ), where they are carried in a pouch formed by the 
coalescence of the broad pelvic fins with the skin of the body, is the female known 
to take any care of her eggs after spawning. Among the bony fishes there are, 
however, several instances where the young are more or less carefully tended by 
the male parent; some, like the sticklebacks, building a nest, while others, like 
certain pipe-fishes, have an abdominal pouch in which the eggs are hatched. 
The eggs of sharks, rays, and chimseroids differ remarkably from those of bony 
fishes, being large in size, few in number, and laid singly instead of in masses. 
They are invested in a hard horny envelope, which is generally oblong in form, 
with the four corners produced, and frequently elongated into tendrils by means of 
which the egg is moored to some foreign substance. The males of these fishes are 
armed with organs known as claspers, which are partially ossified processes arising 
from the pubis, and are evidently connected with the function of reproduction. 
The young of many fishes differ markedly from the adult; and certain peculiar 
creatures with long ribbon-like bodies and small heads, for which the name of 
Leptocephali has been proposed, are believed to be the young of littoral fishes which 
have been carried out to sea, where they have undergone an altogether abnormal 
development. The changes which take place in the flat-fishes during development 
may be more conveniently noticed under the heading of that group. Although 
male and female rays differ remarkably from one another in the structure of their 
teeth, while both in this group and in the sharks and chimgeroids the males are 
distinguished by the possession of the aforesaid claspers, there is generally but 
little sexual difference among fishes. In the bony fishes, however, the females are 
larger than the males; among the cyprinodonts the difference between the two 
being occasionally as much as six times. 
t Fishes exhibit a remarkable degree of difference in regard to 
’ their power of bearing changes from their normal environment. On 
this subject Dr. Gunther writes that, “ some will bear suspension of respiration— 
caused by removal from water, or by exposure to cold or heat—for a long time, 
whilst others succumb at once. Nearly all marine fishes are very sensitive to 
changes in the temperature of the water, and will not bear transportation from one 
climate to another. This seems to be much less the case with some fresh-water 
fishes of the temperate zone; since carp may survive after being frozen in a solid 
block of ice, and will thrive in the southern parts of the temperate zone. On the 
other hand, some fresh-water fishes are so sensitive to a change in the water that 
they perish when transferred from their native river into another apparently 
offering the same physical conditions. Some marine fishes may be abruptly trans¬ 
ferred from salt into fresh-water, like sticklebacks; others survive the change 
when gradually effected, as many migratory fishes; whilst others, again, cannot 
bear the least alteration in the composition of the salt-water (all pelagic fishes). 
On the whole, instances of marine fishes voluntarily entering brackish or fresh¬ 
water are very numerous, whilst fresh-water fishes proper but rarely descend into 
salt water.” 
Distribution The f° re £°i n & remarks lead naturally to the subject of the dis¬ 
tribution of fishes; a subject which the limits of space compel us to 
dismiss with a few sentences. In the first place, we find that many marine fishes 
