2 Prof. H. James-Clark on the Affinities of 
towards the posterior end, which is thickened and rugose. 
The anterior annulations are armed with two fascicles of 
yellow bristles, of about three or four each, placed opposite to 
each other: the rest of the rings have about two each ; but the 
numbers vary. Colour pale orange-red, the mouth with a 
purple cast. Buccal cirri twenty, ten on each side of the oral 
organ, white, beautifully maculated with oblong spots of 
orange-red down the centre. Dorsal cirri reflexed, purple, 
with a faint reddish tinge. 
Length of the worm 2 inches, of the tube 3 inches; diameter at 
larger or anterior end 2 lines. 
This species constructs a rather flexuose tube made of a thin 
horny substance similar to that of the polypidoms of the Sertu- 
larias, and coated with grains of sand and comminuted shells, 
with bits of corallines attached. 
The worm is able to raise its head considerably above the first 
or anterior ring, bearing the dorsal cirri, as shown in the figure 
(Plate I.) on the right. Generally speaking, its movements 
were slow; but when fully protruded it is a beautiful creature, 
the dorsal cirri contrast so strongly with the delicately pated 
buccal organs. I kept it alive for several days, and I found 
that it seldom protruded itself by day ; but as evening closed in 
it would then develope itself to its fullest extent. 
I am, Gentlemen, 
Yours obediently, 
Epwarp Parrirt. 
Devon and Exeter Institution, 
April 21, 1866. 
I].—On the Affinities of Peridinium Cypripedium, Jas-Clk., and 
Urocentrum Turbo, Khir. By Prof. H. James-Crarn, A.B., 
B.S., Soc. Am. Acad. 
In the ‘Proceedings of the American Academy’ of February 
1865 I published a paper on the anatomy and physiology of 
Peridinium Cypripedium, mihi. That article, with the accom- 
panying plate, was copied into the ‘Annals and Magazine of 
Natural History’ for October 1865. In the December Number 
of the same ‘Annals’ I find some remarks on my paper by 
Mr. H. J. Carter, the principal aim of which is to show that the 
animal which I have described is not a Peridinium but a Uro- 
centrum. I wish, through the medium of your Magazine, to 
give my reasons why I did not formerly, and do not now, believe 
that the identification of that gentleman can be sustained. 
Let me state, in the first place, that the whole question hinges 
on the identification of the animal as described and figured by 
