270 
T. Davidson — Wliat is a Brachiopod ? 
The imperfection (one due, I believe, to our slight acquaintance 
with the subject) in the geological record cannot in many cases be 
doubted, but we have no right to make Capital out of unknown data. 
We must tberefore deal witb facts as we find them, and see bow far 
they will bear upon the subject under examination. It may be quite 
true, tbat strata at great distances cannot be positively asserted to be 
strictly speaking absolutely contemporaneous, altbougb tbey may 
contain the same animals. 
Prof. Huxley bas stated tbat for anytbing that G-eology and Palse- 
ontology are able to sbow to tbe contrary, a Devonian Flora in tbe 
British Islands may have been contemporaneous with a Carbonifer- 
ous Flora and Fauna in Africa; but as we have no certainty tbat 
such bas been the case, it cannot be adduced in support of tbe theory 
under notice. It is likewise very probable tbat some species may 
have migrated from the sea-bottom on wbicb tbey originally lived 
to some more favourable locality, and have become to some extent 
modified. No one can seriously doubt tbat life bas continued to be 
represented under one form or another ever since it was first brought 
into existence, and I consequently cannot agree with M. Desbayes 
and others who believe in a total extinction of the animal creation 
at certain specified periods. We are also aware that, taking, for 
instance, the rocks of the Carboniferous period, in almost every 
locality in Europe, Spitzbergen, Newfoundland, America, India, or 
Australia, there are present a few species common to all, in addition 
to a number that are special to the locality. Thus, for example, as 
I have sbown elsewhere, Spirifer lineatus is one of those persistent 
forms, but witb different proportions according to tbe locality, caused. 
no doubt, from tbe sea-bottom being more or less favourable to its 
development. It is consequently very large in tbe Punjab, of mo- 
derate dimensions in Europe, and considerably dwarfed in Nova 
Scotia. Still the species remain essentially the same. 1 
Notwithstanding tbe tbeoretical doctrine tbat bas been promulgated 
with respect to tbe origin of species, we are still and sball probably 
for ever remain in the dark, or within tbe region of suppositions, 
witb respect to so important a question. In bis admirable address 
to tbe Belfast Meeting of tbe British Association, Tyndall observes : 
“ If you ask me wbether there exists the least evidence to prove 
that any form of life can be developed out of matter, witbout demon- 
strable antecedent life, my reply is tbat evidence considered perfectly 
conclusive by many bas been adduced ; and that were some of us 
wlio have pondered tbis question to follow a very common example, 
and accept testimony because it falls in witb our belief, we also 
slionld eagerly close witb tbe evidence referred to. But there is in 
the true man of Science a wisb stronger than tbe wisb to have bis 
beliefs upheld ; namely, the wisb to have them true. And tbis 
1 It has been observed by Eobert MacAndrew tbat although tbe size attained by 
Mollusca (and no doubt by other animals) may be influenced by various conditions in 
different localities, as a general rule each species attains its greatest size, as well as 
its greatest number, in tbe latitudes best suited to its general development ; and 
tbat wbether a species be Arctic, Boreal, Celtic, or Lusitianian, it will grow largest in 
the region to wlücli it belongs. 
