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Prof. J. V. Barboza du Bocage on Hyalonema lusitanicum. 125 
This is pretty nearly what I have replied to Professor Ehren- 
berg; but I am sure that he will maintain his first notion. It 
is his fixed idea. 
There is, however, in what Professor Ehrenberg has written 
to me a question of fact, which I beg you to verify and get veri- 
fied. M. Ehrenberg asserts that he has been able to place be- 
yond doubt the presence of cotton threads attaching the different 
pieces of the Hyalonema. Now I beg you to examine with the 
utmost care the specimens which you possess, and in which M. 
Ehrenberg asserts that he has found this proof of artificial fabri- 
cation, and be kind enough to communicate to me the result of 
your examination. 
For my part I have examined with scrupulous attention the 
six specimens which I possess; and not one of them presents 
the least trace of cotton threads, or anything which would lead 
one to believe in their artificial fabrication. The power of a 
preconceived idea is such that it will make us see cotton threads 
and signs of human fabrication in perfectly natural products in 
which they do not exist! 
The confidence with which M. Ehrenberg writes to me about 
this throws me into the deepest astonishment. On my side 
there is not the least question of self-love. 1 am disposed 
to change my opinion in the presence of good arguments ; 
but I cannot accept as such perfectly absurd hypotheses. I 
have also just read, in the ‘Annals and Magazine of Natural 
History ? (March 1867), the article-by M. Max Schultze. He 
still believes in his sponge ; but, although agreeing on this point 
with Dr. Bowerbank, he does not admit that the polypes also 
belong to the sponge. Quot capita, tot sententia. 
Excuse me for having written you such a long letter, and 
accept, &c. 
J. V. Barsoza pu Bocacs, 
My DEAR AND HONOURED ConFriRE, __Lisbon, June 15, 1867. 
Professor Ehrenberg’s incredulity with regard to the habitat 
of Hyalonema lusitanicum has driven me to undertake a journey 
to Setubal, in order to obtain ali desirable particulars on the 
spot. The following is a summary of the rigorous inquiry 
which I have just carried out. 
The Hyalonemas are well known not only to the shark-fishers 
and the proprietors of fishing-boats, but also to several people of 
good position in the town. They call them “ chicotes de mar,” 
that is to say, “sea-whips.” It is since 1863 that the shark- 
fishers have most frequently found Hyalonemas attached to their 
fishing-apparatus ; nevertheless some persons remember having 
