# Page:Philosophical Transactions - Volume 096.djvu/21

11
and mechanical Action of the Muscles of Fishes.

in a half-penniform manner. The recti abdominis are also divided into short masses by transverse tendons, and all these muscles are conjointly employed in the action of leaping.

Perhaps these observations may indicate the reason for that diversity in the lengths of various muscles, which act together; thus, organs of velocity are joined with those of power, and mutually co-operate to produce a simultaneoui effect.

Description of Plate I.

The drawing was made from a cod which had been coagulated by heat, in a case of plaister of Paris, the skin being taken away, and an equal portion of the flakes carefully removed from each series, to exhibit their several directions. The subject was reduced to the present size by accurate measurements.

${\displaystyle aa}$, Muscles which extend the pectoral and jugular fins.

${\displaystyle bbbbb}$, Oblique muscles, which erect the rays of the single fins.

${\displaystyle cc}$, Muscles which depress the rays.

${\displaystyle dd}$, Muscles which extend the rays of the tail.

${\displaystyle ee}$, Interosseal muscles, which close the rays.

${\displaystyle ff}$, The dorsal series of muscular flakes.

${\displaystyle gg}$, The vertebral series.

${\displaystyle hh}$, The abdominal series.

${\displaystyle ii}$, The ventral series.

${\displaystyle kkk}$, Three superficial nerves which run longitudinally between the series of flakes.

${\displaystyle l}$, Posterior surface of a dorsal flake.

${\displaystyle m}$, Posterior surface of an abdominal flake.

C 2