1880. ] Do Flying Fish Fly ? 653 
as much as the pectoral muscles; and the relation between the 
same in Exoccetus was found, by Mobius, to be as 32.4:1. 
If the work performed by the muscles of flight be proportional 
to the weight of the body, then, as Mobius observes, the pectoral 
fin-muscles of Exoccetus must develop about five times as much 
force as the pectoral ‘muscles of birds, and about two and one- 
half times as much as the same muscles of the bats. 
The objection from this point of view has been greatly over- 
estimated by Mobius. As flying fish generally move their pec- 
torals during only a part of their flight, which is at most short, 
they do not need to expend so much muscular energy as birds 
and bats, which take long continued flights. Small muscles may 
perform, for a brief period, work which only larger muscles would 
be able to perform for a long time. Mobius. seems to have over- 
looked the fact that zime, as well as size, is an element of this 
problem. 
Perhaps also the large air-bladder may, as Humboldt supposed, 
have something to do with lightening the work of the muscles, 
while serving as a store-house of oxygen. 
The experiment of Humboldt, by which he determined that 
the fin-rays of Exoccetus move with five times greater force than 
the rays of other fins, would seem to favor the opinion here 
maintained, 
Admitting that in form, size, length and structure the pectoral 
fins of Exoccetus are less well adapted to flight than the wings of 
most birds, there is still ample room to believe, on anatomical and 
Physiological grounds alone, that they are capable of executing 
true flight. Te 
In regard to the personal observations of Prof. Mobius, it may be 
said that they can lay no claim to the right of deciding this ques- 
tion. Whatever evidence they afford is of a purely negative 
character; and of this fact Prof. Möbius seems to be fully aware, 
if we may judge from the stress which he lays upon other con- 
siderations. 
That Möbius and others may not have been fortunate enough 
to recognize the wing-like motion of the pectorals, establishes a 
most only a probability, which weighs very little against the 
Positive evidence afforded by the testimony of those who have 
actually seen flying fish fly. 
