vine: YORKSHIRE carboniferous and PERMIAN POLYZOA. 185 
litliographer have enabled both author and artist to give very full 
delineations of a most remarkable group of fossil organisms. Still 
the nomenclature of many of these fossils is unfamiliar to Briti.sh 
students, and this alone will necessitate my giving prefacial intro- 
ductions to every new group of our Yorkshire fossils. In this, I do 
not think I shall be accounted tedious by the real student, for the 
simple reason that an accurate appreciation of a fossil form is a step 
in the right direction towards the proper classification of the same . 
Another very elaborate wi'iter on American Palaeozoic Bryozoa 
(= Polyzoa, in part), is Mr. E. 0. Ulrich. I have before me nearly 
the whole series of Mr. Ulrich's papers, but the long-delayed mono- 
graphs, vol. VIII. of the III. Geological Survey of Illinois and 
Minnesota, are still unpublished, and cannot be refeiTed to for details. 
The plates, however, of these two works, by the kindness of Mr. 
Ulrich, are in my possession, and I cannot withhold my admiration 
of the way in which the Silurian, Devonian, and Carboniferous 
Polyzoa of Illinois and the Lower Silurian groups of Minnesota have 
been treated by the author. One advantage I enjoy in referring to 
the text of Mr. Ulrich's unpublished report is the reproduction of a 
part of it, in a separate paper, on " Waverly Bryozoa," which con- 
tains a list of the species occurring in Ohio, vvith descriptions and 
illustrations of new species.'" I have already, when Avriting on 
Cystodictyonid?e (part I.), referred to the plates belonging to the 
Illinois report, but, because they contain figures of several American 
Carboniferous Polyzoa, closely allied to the British fauna, I shall be 
obliged to refer to them again and again. The plates Ixx. and Ixxi.f 
are wholly occupied with figures of Rhomhopcyra and species of 
Htrehlotrypa , in all twenty-four species. Many of these forms are 
similar to Yorkshire examples, so much so that some of the figures, 
only with different names, would serve as illustrations of most of the 
Yorkshire Rhomhopora, and Rhahdomeson at least, whilst others 
would justify our placing a larger series before the student of York- 
shire Polyzoa, having distinct specific names, than under present cir- 
cumstances I am warranted in doing. Out of the twenty-four 
* Bulletin of the Laboratories of Denison University, Granville, 0., Dec, 1888. 
t Geol. Survey, Illinois, vol. viii. 
