202 REPORT—1885. 
In spite, however, of all that has been written about this ‘laminar axis” 
in Polyzoa, I have always had my doubts about its existence, and I did 
not care to venture into the domain of mere disputation until I could 
give some tangible proof that my views were correct. I ventured to 
touch upon the question in my paper on the ‘Wenlock Polyzoa.’ In 
that paper I wrote (op. cit. p. 66), when speaking of Ptilodictya 
Lonsdalei, Vine: ‘I refuse to say cells ‘‘separated by a thin laminar axis,” 
because this is not so in this species at least. The “ axis,” if such it may 
be called, is formed by the bases of the cells, both in transverse and in 
longitudinal sections.’ After giving the views of Mr. John Young of 
Glasgow, and also recording my own observations on the specimens in 
the School of Mines, and the observations of Prof. Nicholson, I pass on 
to say: ‘This being a matter of extreme importance, I shall return to its 
discussion at some future time when other investigations which I am 
making are completed.’! I cannot say whether or not Mr. Ulrich has 
seen the above remarks. If he has not, I must then take his testimony as 
independent, but in October 1882,? when criticising remarks made by 
Prof. Nicholson (‘ Monticulipora,’ p. 196, 1881), Mr. Ulrich says: ‘If I 
understand him (Nicholson) correctly, he believes that the axis is con- 
stituted by a definite structure from which the two layers of cells may be 
stripped. This impression is manifestly erroneous, nor do I know of a 
single double-leaved Bryozoon in which such a structure may be demon- 
strated. In Ptilodictya the facts are simply that we have two layers of 
cells which are grown together back to back by the adhesion of the 
epithecal laminz of each layer.’ So far the observations of Mr. Ulrich 
agree with my own, but because of this I am not prepared to accept the 
farther view that Monotrypa pavonia, D’Orb. (‘ Monticulipora,’ p. 195), is a 
Ptilodictya (‘ American Pal. Bryozoa,’ pp. 163-4).3 Itis very evident that 
our Silurian rocks are remarkably poor in species of Ptilodictya, and it 
gives me great pleasure to acknowledge the varied labours of Mr. Ulrich 
and Mr. J. M. Nickles in working out what they prefer to call 
‘ Bryozoa.’ 
VII. The endosarcal passages. If we are to accept the views of the 
leading writers on the development of Polyzoa, then some little attention 
should be given to what I venture to call ‘endosarcal passages’ in the 
zoarium of fossil species. Whenever we examine with a high power the 
supposed contiguity of the cells, we generally find between the ‘ epitheca ’ 
of cell and cell very delicate hollow spaces. In longitudinal sections of 
Ptilodictya the hollow spaces intervene all along the so-called ‘laminar 
axis,’ and the alternate cells at their bases appear to open into this tube- 
like hollow. In Fenestella, and also in various species of ‘ Pinnatopora,’ 
I have detected similar hollows. In the Graptolites the ‘cellules’ of 
certain species open into what is called the ‘canal,’ a space intervening 
between the ‘solid axis’ and the cellules, through which the ‘ organic 
pulp passed into the cells.’ I have not the least doubt but that through 
these passages in the ancient zoaria of the Polyzoa the endosare passed 
from cell to cell. It is not in every section that I have made that I have 
been able to detect the passages ; still they are found in some, and I have 
2 Read Dec. 1881. Pub. Quar. Jowr. Geo. Soc. Feb, 1882. 
2 American Paleozoic Bryozoa, p. 164. 
3 Thave a specimen of Monotrypa pavonia, D’Orb., from the Cincinnati beds, 
before me while I write. 
eo 
