TRANSACTIONS. 
O71 a species of Filamentous Diatom new to Britain. 
By Arthur S. Donkin^ M.D., Morpetli. 
(Read June 10th, 1857.) 
In the ^ Quarterly Journal of Microscopical Science/ 
vol. iv, p. 105_, Mr. Briglitwell,, in a communication on the 
filamentous long-horned Diatomacese^ describes two species 
of these singular Algae as the first which have been_, in a 
living state^ discovered in this country : these are Chceto- 
ceros Wighamii, gathered by Mr. Wigham_, at Breydon^ near 
Yarmouth^ in July, 1854; and Goniothecium hispidum, since 
found with the preceding, in the bay of the Isle of Roa, near 
Ulverstone. Since the date of Mr. BrightwelPs communica- 
tion, no other native member of the family has, I believe, 
been discovered. 
Within the last few days, however, it has fallen to my lot 
to discover a third species in a recent condition, which, if I 
am not mistaken, has hitherto been found only in a fossil 
state in certain diatomaceous earths, and in the guano de- 
posit on the coast of Peru ; from which it appears to possess 
a very wide geographical range. This species is the Synden- 
drium diadema of Ehrenberg, easily recognised by the pecu- 
liar form of its frustule, with its numerous styles having 
branched extremities proceeding from its larger or more 
convex surface. This species was discovered in the following 
manner. A few days ago, I purchased a lobster taken ofi:' 
the Cresswell coast, nine miles to the east of Morpeth, not 
far from low- water mark, where the sea bottom is covered 
with flat rocks and the larger Algse luxuriant. After sub- 
jecting the contents of this lobster^ s stomach to the action of 
boiling nitric acid for several minutes in a small retort, and 
after removing the acid from the remaining sediment by re- 
peated ablutions with distilled water, I was not a little 
astonished to discover on all the slides — on which a portion 
of this sediment was placed — several specimens of Synden- 
drium diadema; its frustules being more numerous than 
those of any other diatom. From this fact it would appear, 
that this remarkable form is quite common on this part of 
the Northumbrian coast (but this I mean shortly to ascer- 
VOL. VI. d 
