200 FISH—CULTURAL ASSOCIATION. 
oviparous. We all know how false such a statement is. In one 
class, the Sedachians, the larger proportion of forms are vivipar- 
ous. For example, of the sharks proper, three-fourths, or more, 
are viviparous, and the same statement holds good with respect 
to the rays or skates. Thus, out of 150 species of ravs, over Ioo are 
viviparous, and another noteworthy fact is that the oviparous 
rays are nearly all included in one family—the common skates 
or rays brought to our markets. This feature of viviparity was 
known to the ancient naturalist, Aristotle, who even went so far 
as to say that the Se/achians were viviparous, while all scaly fishes 
were Oviparous. There, however, he erred, for there is no such 
limitation. Many of the Se/achtans are oviparous, and, on the 
other hand, many of the scaly fishes are viviparous. For in- 
stance, all the Zmédiotocoids are viviparous; and of these the com- 
mon perch of the Pacific is an example; also viviparous are the 
eelpout of our markets, and species of the Cyprinodont family 
among others. Viviparity is, indeed, largely manifested among 
fishes. The only reason why reverse statements are found in 
the old books is that in Europe these cases were almost un- 
known. 
I agree with the statement of Mr. Ryder that confinement fre- 
quently affects the power of procreation, either directly or indi- 
rectly, and this does not apply to fishes alone, as is evident from 
the experience of those in charge of menageries and zoological 
gardens. It is knownsthat many animals and birds which are 
confined seem to live with perfect freedom in zoological collec- 
tions, but they do not bring forth young, or their eggs are ster- 
ile. There are many exceptions to this rule, but many cases of 
sterility for which we can assign no other cause. Somewhat 
anologous is the peculiar pathological condition of animals 
living in confinement, in which the bones become softened or 
rickety. 
