34 
VINE : CLASSIFICATION OF THE PALEOZOIC POLYZOA. 
error of judgment on my part, but no great sin at a time when so 
little was known about our British species. Since then my knowledge 
has been widened, and I owe to Mr. Ulrich's friend, and my own, 
Mr. J. M. Xickles, ample American material from the Cincinnati 
rocks, to show that the location may have been a bad one. I quote 
my own remarks, and I will later on reproduce my original illustra- 
tions, which were drawn for the purposes of the Report in 1879. 
The structure therefore which formed the basis of the character of 
Cystodictya, Ulrich, were known to, but not fully appreciated by me 
at the time I wrote. In the same report," however, I separate the 
Sulcoretepora Rohertsoni, Young & Young, from FJ parallela, remark- 
ing that >S'. Rohertsoni is destitute of the non-poriferous, rugose, and 
striated margins of F. parallela. It is upon the presence of this 
particularly constant character that I refer Phillips' species to 
Ptilodictya!^ This correction of my former work was needful, and I 
make no apology for its introduction here. The remark however 
does not apply to my nomenclature of the minute structures of P. 
lonsdalei, Vine, which I used as the basis of the sub-divison Cryptos- 
TOMATA . 
" Zooecia tubular, sub-tubular, in section (occasionally) slightly 
angular. Orifice of cell surrounded by vestibule, concealed." 
I am not prepared at present to say what species will be included 
in the group, but I wish the student to bear in mind that my 
arrangement is based upon the "cell" rather than upon the 
surroundings of the cell, and that I still retain Ptilodktya lonsdalei 
(Stictopora ?) and its peculiar structures as typical of the division. 
III. Sub-order Trepostomata, Ulrich. 
There are several species in British Silurian Rocks that may be 
conveniently placed in this sub-order, notably the Pseudo-Polyzoan 
forms referred to in the Fourth British Association Report (p. 45 of 
Report). Many of these species are still awaiting description and 
illustration, but I have preferred to keep them in abeyance till the 
report of Mr. E. 0. Ulrich is published ; but the groups Monticuli- 
pora and Fistulipora have been so ably handled by Prof. Nicholson 
* Ibid, p. 8 of Report, 
