The repeated

observation of this phenomenon has led to the
notion that the process was equivalent to coition, but the fact is
that a similar phenomenon is observable in quadrupeds. For at the
rutting seasons both the males and the females take to running at
their genitals, and the two sexes take to smelling each other at those
parts. (With partridges, by the way, if the female gets to leeward
of the male, she becomes thereby impregnated. And often when they
happen to be in heat she is affected in this wise by the voice of
the male, or by his breathing down on her as he flies overhead; and,
by the way, both the male and the female partridge keep the mouth wide
open and protrude the tongue in the process of coition.)

The actual process of copulation on the part of oviparous fishes
is seldom accurately observed, owing to the fact that they very soon
fall aside and slip asunder. But, for all that, the process has been
observed to take place in the manner above described.