Feb. 9, 1871] 

; ee one another, to dovetail into each other, and gradually to 
lend one into the other, both in lithological character and fossil 
contents, 
Will any palzontologist take it on himself to say that there 
is a greater difference between the fauna of the Atlantic chalk 
and the chalk of England, than there 1s between the lower and 
upper divisions of the rocks of the Carboniferous period 2? Of 
course the Atlantic chalk is not to be represented only by the low 
forms found in the deep-sea soundings, as they do not represent 
its entire fauna, Years ago the late Mr. Salter pointed out at 
Glengariff, Co. Cork, that more fossils occur at changes of strata 
than elsewhere; such as the uppermost limits of a series of 
argillaczous or arenaceous beds, or at the top of a bed, if grits 
and shales alternate. This I have since found to be a good 
general rule, more especially when subordinate beds appear in a 
group. In Limerick, as well as other places in Ireland, masses 
of limestone may be without fossils, or, at least, conspicuous 
fossils ; but if subordinate beds appear, such as the cherty zones, 
the aspect of a‘fairs immediately changes, and, as a general rule, 
the rocks immediately subjacent to such changes are almost en- 
tirely made up of fossils and their @éris. Similar changes are 
not only possible, but also most probable, in the Atlantic chalk. 
However, they are not likely to be proved in our day. But as 
in the limestone, so in the Atlantic chalk, in such places the 
mass of the fossils belonging to the latter ought to be found. 
In considering such a question as the present, I would suggest 
that such fragile accumulations as those of the Kainozoic 
epoch ought to be considered of only minor importance ; as 
most of them would be denuded away as the land sank, while 
those that chanced to remain would only form very subordinate 
strata. Moreover, Edward Forbes long since suggested that both 
from palzontological and petrological considerations, it might 
be better if the division between the Mesozoic and Kainuzoic 
epochs were obliterated. Furthermore ‘t has to be borne in mind 
that while in new strata very minute breaks can be detected ; in 
old strata, like the Carboniferous period, it would be nearly 
impossible ; and most of the great advocates for the minute 
division of the newer rock would not allow them inthe old, as 
they explain everything they cannot understand bya ‘‘ fault.” 
Connemara, Jan, 29 G, Henry KINAHAN 
Eozoon Canadense 
THE organic nature of Eozodn Canadense may, I trust, be 
regarded as established conclusively by the evidence which has 
been adduced by Ur. Carpenter, Dr. Hunt, and myself, and I 
think I am safe in saying that it is accepted by all or nearly all 
those best qualified to judge. Since, however, the doubts 
expressed by your correspondent, Mr, Reade, may be shared by 
many who have not had full opportunity to satisfy theniselves on 
the subject, I think it may be useful once more to direct attention 
to the facts serving to answer the objections which he has stated, 
and wh ch, on more full consideration of the questions involved, I 
trust he may abandon. 
Your correspondent objects: First, That the supposed Liassic 
serpentine or ophiolite of Skye shows structures simi‘ar to those 
of kozobn. In answer to this it is not necessary to have 
recourse to the supposition that creatures similar to Ifozodn have 
continued to exist up to the Liassic age, since, as Dr. Hunt hs 
shown,* there is reason to doubt the accuracy of the observa- 
tions which refer this rock to the Li's; and, further, Profs. King 
and Rowney, in a recent paper on Eoz96n in the Proceedings of 
the Royal Irish Academy, have figured this supposed Eozo6n, 
and have thus shown that the portions of it which they consider 
similar in structure to the Canadian specimens do not possess 
such structure. I would not, in any Canadian specimen, accept 
such appearances as those represented in their figure as the 
Eozoén. ‘This objection is therefore wholly irrelevant. 
He objects ; Secondly, That Kozodn occurs only in meta- 
morphic rocks, and usually mineralised by serpentine. To this I 
answer: (1.) It unfortunately happens that Iozo6n is a fossil of 
the Laurentian period, and that the rocks of this age are in a 
more or less metamorphic state in every part of the world where 
they are known. Wen we shall have found unaltered 
Laurentian :ocks it will be time to inquire if this fossil occurs in 
them, and in what state of preservation. (2.) I have elsewhere 
shown that the chambers an! canals of Eozodn are filled not 
oaly with serpentine but with other mineral substances, as 
* Silliman's Journal, March 1870, 
+ Proc, RIA, July 18€9. 
NATURE 

287 

Loganite, Pyroxene, and Calcite. There is thus, as Sir William 
Logan affirmed previous to the discovery of the minute micro- 
Scopic structure, no connection between the forms of the supposed 
organism, and the mineral substances in connection with which 
they appear, 
In the third place, in order to be enabled to make the assertion 
above referred to, your corr spondent “disposes of * the Tudor 
specimen, which, as compared with the others examined, occurs 
ina _compnratively uniltered sediment. With regard to this 
specimen, Taffirm, and the published figures show: (1) that it 
presents the characteristic features of Eozodn, more especially 
resembling the specimens from the Calumet and from Perth; 
(2) that other specimens found in the same locality confirm its 
determination as Mozo6n; (3) that the matrix containing the 
Tudor specimens is a coarse limestone not more metamorphic 
than many Silurian beds holding fossils. I have, however, to 
state that the recent explorations of Mr. Vennor, of the Geological 
Survey, seem to show that the beds which afforded the Tudor 
specimen, though unconformably underlying the Lower Silurian, 
overlie the highiy metamorphic Lower Laurentian of the district, 
and, therefore, ins'ead of being, as heretofore supposed, com- 
paratively unaltered Lower Laurentian, they may prove to be 
even as late in age as the Cambrian. It is in these rocks that the 
worm-burrows which I observed some time ago occur, * 
Fourthly, he alleges imitative forms which Profs, King and 

Rowney consider to be ‘‘ identical with the thing itself.” Now, 
imitative forms are not unknown to palzontologists. I have 
seen rill-marks figured as fossil leaves, and trails of worms and 
other mere markings, as fossil plants of various kinds ; and many 
dendritic crystallisations are wonderfully like mosses and alge. 
I have on my table at this moment a curious group of rounded 
concretions of black oxide of manganese in a coal-formation 
sandstone, which I received a few days ago from a very judicious 
collector, who believed that it was an undescribed fiuit. But 
such things do not invalidate the evidence of real fossils. It is 
to be observed, however, that while it is extremely easy to assert 
that such imitative forms are identical with fossils, and even to 
make this appear plausible in descriptions and drawings, careful 
examination of actual specimens, with attention to chemical con- 
ditions and modes of occurrence, may be necessary in order to 
draw the proper lines of distinction. In the case of Eozoon, 
the imitative form has neither been shown to unite the general 
arrangement, microscopic structure, and mode of occurrence of 
the fossil, nor perlectly to resemble it in any one of these respects. + 
In so far as my own comparisons have extended, I am prepared 
to demonstrate the difference between all such crystalline, den- 
dritic, and concreticnary forms, and the Canadian Eozcén. 
Your correspondent merely confines himself to general asser- 
tions and to starting difficulties. His authorities, Profs, King and 
Rowney, in the paper above referred to, have ventured on the 
niore dangerous ground of constructive criticism, and have 
endeavoured to explain the way in which they suppose Eozoén 
to have been produced. In doing so they have been obliged 
to resort to an extravagant and complex theory of pseudo- 
morphism, which I fancy most of the palzontologists will 
throw down in despair of comprehending it, and which I am 
sure any competent mineralogist or chemical geologist who 
studies it, will reject as much more trying to his faith than 
anything required to explain the occurrence and preservation of 
Eozo6n as a fossil. 
Lestly, your correspondent desires further investigations with 
reference to the questions involved in the organic character 
of Eozoon. Jt may satisfy him to be informed that Dr. Hunt 
and I have just sent to Dublin a reply to the objections of 
Profs. King and Rowney, in their paper above referred to; and 
that I have for some time been pursuing investigations of Pri- 
mordial and Silurian fossils akin to Eozo6n either in structure or 
mode of preservation. When these investigations are completed, 
I hope to show that Eozo6n has several foraminiferal successors 
in the older palzeozoic rocks of Canada, and that fossils of 
various kinds occur in those rocks infiltrated with mineral mat- 
ters in a manner not dissimilar from that observed in the Lau- 
rentian Eozoon, J. W. Dawson 
McGill College, Montreal, Jan. 18 
Natural Science at Cambridge 
“M.A.” will best satisfy himself as to the grounds for the sen- 
tence which appeared in Nature for January 12, to which he 
* Journal of Geological Society, xxii. 608. ne 
+ Messrs, Rowney and King themselves virtually admit this. 
