78 
and measurements, having been published by me in the 
‘Ann. & Mag. Nat. Hist.’ in July, 1851. The identifica- 
tion of the coccoliths of the soundings with those of the 
chalk (to the last of which attention was drawn by E hr ten- 
berg and Mr. Sorby) was announced for the first time in the 
two papers just referred to, Mr. Sorby’s paper having 
appeared in the ‘Annals’ in September, 1861. In this 
paper Mr. Sorby actually refers to the spheroidal bodies 
under the name I gave them. The merit of the identifica- 
tion spoken of by Prof. Huxley, such as it is, I have there- 
fore a right to claim as mine. 
The coccoliths, however, cannot correctly be said to be 
“ aggregated together into the spheroids,” as stated in the 
lecture They are in reality arranged, at intervals, over the 
surface of the spheroidal cell, on which their concave sur- 
faces rest, and which is, to this extent, a separate portion 
of the structure. When detached, as they invariably appear 
to be in the chalk and the fossil earths (of which I shall 
have occasion to say a word presently), they bear the same 
relation to the supporting cell that the fallen fruit bears to 
the tree that bore it, and nothing more. 
Of their true position in the organic world I am ignorant. 
But I have these important facts to add (referred toby me 
incidentally in a paper on “The Polycystina,” which was 
read before the Royal Microscopical Society in May, 1865, and 
published in the ‘ Transactions ’ of that Society), that I have 
detected coccoliths in abundance, and retaining their normal 
characters, in some of the fossil siliceous earths of Barbadoes, 
&c., and that coccospheres have been met with by me pro- 
fusely in a living, or perhaps it would be more safe to say a 
recent, condition, in material collected at the surface of the 
open seas of.ihe tropics, and also in dredgings from shoal 
water obtained off the south coast of England. 
It only remains for me to add that, so far as the chemical 
nature of these bodies can be ascertained by reagents and the 
polariscope, there is reason to believe that carbonate of lime 
enters largely into their composition ; and they furnish us 
with another striking example, in which simplicity of struc- 
ture has enabled an organism to weather the vicissitudes to 
which the surface of the globe has been subject, and under 
the operation of which more complex forms have ceased to 
exist. — Athen<Bum for Sept. 19, 1868. 
Prof. Huxley, at Mr. Sorby’s request, replied to this letter 
and defended Mr. Sorby’s claim. See also his paper in the 
last number of this Journal. 
