Prof. W. King on Spirifer cuspidatus. 9 
specimens, and supposed to be the remains of perforations. 
This and other considerations prevent me from admitting that 
Mr. Davidson’s specimen was always imperforate—that is, 
that it absolutely possesses or possessed this negative character. 
It will have been seen that, with the exception of the last 
three specimens, all the rest show perforations more or less 
plainly, but associated with others which exist in a very ob- 
scure condition—so much so that, were it not for their occur- 
ring in the required place, and being slightly different in 
translucency, they might be objected to as representing any- 
thing of the kind: between the latter and the former, however, 
there indisputably occur all the intergraduating forms. More- 
over perforations often unexpectedly appear in the midst of 
wide imperforate spaces—a fact admitted both by Mr. Meek 
and Dr. Carpenter. 
Now, as the perforations of Spirifer cuspidatus occur in all 
states of appearance, from the extreme obscure to the perfectly 
obvious, is it not reasonable to suppose that they may also 
occur under such conditions as to be imperceptible, and thus give 
rise to seemingly “imperforate spaces ?’’ Why the perfora- 
tions are partially absent in some specimens, also totally ab- 
sent in others—I do not feel myself competent to go beyond 
suggesting that the cause may be in some way or other con- 
nected with the metamorphism or mineralization of the test. 
But Dr. Carpenter declares himself to be strongly in favour of 
a different view. He “feels certain” that the absence of the 
perforations ‘is not the result of any alteration produced by 
fossilization, the shell-structure being equally well preserved 
in the perforated and in the imperforate parts”*. The state- 
ment may be taken for a fact; but I totally dissent from the 
conclusion drawn from it. A few observations on this point 
may now be brought forward. 
The fact mentioned by Dr. Carpenter is certainly a remark- 
able one. It, however, not only holds good in the “ perfo- 
rated” and “imperforate parts,” but equally so in those which 
show the perforations very obscurely. 'The present condition 
of such perforations is indisputably “ the result of alteration ;” 
yet how does it happen that their associated fibres are “‘ equally 
well preserved ”’ as in the other cases? Because, from certain 
incidental causes and structural peculiarities, to be shortly 
noticed, “ fossilization’’ has had the effect of (nearly in many 
cases and entirely in others) obliterating the perforations, with- 
out producing any such results in the “ shell-structure.” The 
existence of the cases just referred to is not to be taken simply 
* Ann. & Mag. Nat. Hist. July 1867, p. 71. 
