60 
Norman, on Diatomacem. 
observation extended over a longer period of time. The 
following species were collected by myself (with the few ex- 
ceptions I have mentioned) within the short period of little 
more than three years. 
It may perhaps be objected to, that species have been in- 
cluded which strictly speaking have not occurred in this 
neighbourhood. I allude here to the various forms collected 
from Ascidians taken from Oysters, dredged some 30 miles 
from the Humber mouth ; but when I state that these Asci- 
dians may always be found on Oysters in the Hull market 
during the winter months, I think the objection is overruled. 
Again, I have thought proper to include one or two species 
collected in the Docks from the bottoms of vessels recently 
arrived from abroad. In so doing, my object has been to 
point out this source for many interesting forms, and to sti- 
mulate others to examine vessels arriving in our various ship- 
ping ports. Dlaioma hyalinum and Hyalosira delicatula have 
occurred to me copiously in such localities. 
I have already stated, that — with few exceptions — the 
species enumerated in the following list have been collected 
and identified by myself, consequently I alone am responsible 
for the correctness of the same. 
The exceptions are the species and localities furnished by 
Mr. Robt. Harrison, and Dr. Munroe, to whom my best 
thanks are due. 
It will be seen that I have included the Genera Rhizoso- 
lenia, Dicladia, Choetoceras, Syndendrium, and Bacteriastrunij 
which may or may not with propriety be considered as true 
Diatomacese. They are however, in my opinion, so closely 
allied that I have not hesitated to admit them. 
Epithemia, Kiitzing. 
E. turgida, Sm. — Not uncommon. RisbyPond. Peat Deposit, 
Hornsea. Plentiful in a pond. Stepney Lane. 
E. Weste7inann, Sm. — Rare. North Humber Bank, Dr. 
Munroe. 
E. Hyndmanii, Sm. — Rare. Peat Deposit, Hornsea. 
E. gra7iulata J Kiitz. — Rare. Hornsea Mere. Hornsea Deposit. 
E. Zebra, Kiitz. — Not uncommon. Hornsea Meer. Drifl&eld. 
River Hull^ Wawne. 
E. Argus, Sm. — Rare. Hornsea Deposit. 
E. alpestris, Sm. — Rare. Hornsea Deposit. 
E. proboscidea, Kiitz. — Local. Tetney Lock. Hornsea De- 
posit. 
E. Sorex, Kiitz. — Rare. Pond in Stepney Lane, copious. 
