ill!Ill

COLLECTING DIATOMS. 3 1
timber has remained for any length of time afloat before shipping,
the logs are almost sure to have traces of Confervas, either fresh water
or marine, growing on them, and these, on being carefully scraped off,
will, in all probability, yield diatoms to reward the collector. Some of
the logs from the St. Lawrence or the Ottawa will yield us American
forms, while logs from Dantzig will give us interesting gatherings from
the Vistula and the interior of Poland.
"Should a vessel be unloading
"
Kaurie spars" from New Zealand,
or some of those gigantic
" "
sticks which have lately been imported
from Vancouver's Island, we may probably be rewarded by finding
beautiful Antipodean forms of Diatomaceae on the former, and the
exquisite Arachnoidiscus or Triceratiuin IViikesii from the latter perhaps
even Aulacodiscus Oregonus.
" Let us not go past these mahogany logs landing
from Mexico or
Honduras, as the case may be, without casting an eye over them, for
these may have been rafted for some time in the sea before ship-
ment, or may have brought down new or little known forms from the
interior of Central America. Here, on the first log we examine,
copious incrustation of a form either identical with or closely
is a
allied to
Melosira nummuloides, abundant likewise in our docks. The gathering
is so copious that it fairly glistens
in the sun.
"Let us also scrape away some of the shelly incrustation of Ba/anus,
which completely covers some of the logs, for possibly among this we
may find that exquisite American form Terpsinoe musiea, so called, I
suppose, from the costal appearing like so many musical notes.
"
Here are some fishermen just coming in. Let us examine their
nets, for these men are trawlers, and have been fishing in deep water,
and the meshes of their nets may still have diatom-bearing Algae
attached to them. On such Algae we may probably find Rhabdonema
arcuamm or Adriaticum, Grammatophora serpentina and marina, with
species of parasitic Synedras ; possibly the singular Synedra undulata
may reward our search.
" Some of the oyster shells from deep
water are worth examin-
ing for marine Algae, or, what is even better, the greenish, leathery-
looking ascidians attached to them. The ascidians are regular feeders
on diatoms, and their stomach contents often yield a rich harvest of
deep-water forms difficult to obtain in any other way. Perhaps we
may be securing the rare Biddulphia regina, at any rate Biddulphia
Baileyii and aurita. We will take some for future examination, for
the curious Rhizosolenia styliformis
is almost sure to be there.