80 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
Whether they actually find nutriment in the jeily-fish itself, or 
whether they are in pursuit of young fish or crustacea that so often ac- 
company the medusa, I am unable to say. 
The habit of association between the jelly-fish and other species is 
a very curious one. In Norway the association of young cod and had- 
dock with the Cyanea arctica is well known, Professor Sars having 
called attention to it, and having furnished specimens of fish taken 
under such circumstances to the National Museum at Washington. 
It is a very common thing to finda number of young harvest-fish, dol- 
lar-fish, or butter-fish (Stromateus triacanthus), swimming near the jelly- 
fishes, and running under them for protection on the approach of an 
enemy; indeed, I have seldom found very young butter-fish except in 
association with the medusa. Young hake are frequently found ina 
similar association. ; 
G.—REPRODUCTION. 
The last division of our topic of the natural history of fishes relates 
to the subject of their reproduction, and I now proceed to give a brief 
statement of the more interesting facts of this character. The repro- 
duction of fishes is, for the most part, by means of eggs discharged from 
the body and hatched externally to it, these eggs when emitted being 
either adherent to each other and to whatever they touch, or free, float- 
ing near the surface of the water, or sinking to the bottom. Not* un- 
frequently the parent covers up the eggs in furrows excavated by a 
rapid movement of the tail. Occasionally the eggs are discharged in 
large masses, notably so in the case of the Lophius, or fishing-frog, 
where they are imbedded in a shell of jelly, sometimes 50 feet or more 
in length and several feet wide. In some instances adhesive eggs are 
attached to the body of the parent, where they remain until the young 
are hatched out. Atother times they are carried in a pouch under the 
abdomen, most frequently of the male, as in the pipe-fish (Syngnathus) ; 
sometimes of the female, as in the Solenostoma. Occasionally regular 
nests are prepared (again generally by the male) usually of vegetable 
substances, as in the case of the sticklebacks, in which case the eggs 
are hatched and the young cared for by the male. Numerous other 
varieties of presentation could be mentioned, but these are sufficient 
for my present purpose. In not a few instances the eggs are retained 
in the bcdy of the parent until they are fully developed, although with- 
out placental adhesion, except in a modified degree in some of the 
sharks. In one family, that of the Embiotocoids, of the Pacific coast 
of California, not more.than five to ten or fifteen young are produced at 
a birth, these sometimes being 3 or 4 inches in length, from a parent of 
not more than 8 or 10, 
Certain species of sharks and sting-rays produce living young, some 
showing an indication of placental relation to the mother. In all cases 
Se See eS ee 

