ver, there were so many of
them together, and they kept so continually moving about, that I
could not single out the two individuals, and thus ascertain
whether they were male and female; but I felt so desirous of being
able to set this question at rest, that I went again next morning,
and was fortunate enough to find only two, a male and a female. I
then witnessed several sexual conjunctions, during which the sand
and small gravel was stirred up by them, and each of which was
followed by the ejection of a jet of eggs from the female. I then
caught them both, and dissected them. The sexual organ in the male
was projected above a quarter of an inch, and the body filled with
milt; the female, although she seemed to have shed a considerable
quantity of her spawn, had still a tolerable stock remaining.

I frequently afterwards witnessed the same thing, and always found
the same difference of sexes; in fact, there was generally no
difficulty in distinguishing the male from the female, without
taking them out of the water: the latter might be readily known by
the enlargement of her body, and the former by a still more
incontestable token. I have been induced to describe this more
minutely than I otherwise should have done, in consequence of the
mystery in which the propagation of fish has been wrapped
hitherto; and I am not aware that what I have described has been
witnessed by anyone before--at least I don't know that it has been
recorded.

I caught half-a-dozen Lampreys, four males and two females, and
preserved them in spirits, and these I now forward to you.

I am unable to give the same information concerning the large
Lamprey, having never seen it in the act of spawning; but I have
repeatedly caught both milters and spawners of species with the
milt and roe as distinctly visible in them as it is in the Salmon
or any other fish.

I am of opinion that the _P. marinus_ and the _P. fluviatilis_ are
distinct species, for the following reasons:--1st. Because the
latter stays with us the whole year, while the former only ascends
the rivers to spawn, and then returns to the sea immediately. 2nd.
Because fish that are in the habit of descending to the sea, never
(unless the small Lamprey be an exception to the general rule)
arrive at maturity [13] until they have visited it; and, 3rdly,
because there are no intermediate sizes (at least in the Ribble)
between the one which, although only six or seven inches long, and
an ou