186 vine: YORKSHIRE CARBONIFEROUS AND PERMIAN POLYZOA. 
American types as figured from the Illinois rocks, the most noticeable, 
as apparent allies of our own, are the following : — 
1. Rhombopora minor, IJlrich, pi. Ixx., fig. 4. 
2. „ angustata, Ul., „ figs. 6, 6a. 
3. ,, atteniiata, UL, ,, fig- 7. 
4. exigua, UL, ,, figs. 10, lOrt. 
5. ,, incrassata, UL, ,, fig. 12. 
6. „ dichotoma, UL, ,, fig. 18. 
7. Streblotrj^ia major, UL, pi. Ixxi., fig. 8. 
8. „ nicklesi, UL, „ fig. 9. 
Unfortnnately [or fortunately ?] in onr own Carboniferous rocks, 
the range of variation of Khomhopora and lihabdomeson species is so 
great, and the links by which the separate examples may be united 
the one to the other so many, that about fou.r specific names serve to 
include a large amount of ordinary variation. Hence the vast 
abundance of British Carboniferous faunal remains of the once wide- 
spreading Rhombopora, Rhahdomeson , and Fenestella groups, compel 
the conscientious British Palaeontologist to pause before the creation 
of new specific names for the rarer offshoots, shall I say ? of the more 
common species. This restriction reduces our lists of names con- 
siderably, and thus, apparently, the British Carboniferous fauna is 
less interesting to the ordinary student than, judging from names 
only, the more abundant American Polyzoal fauna. It must not be 
assumed from the above remarks that I in any way doubt the 
accuracy of the specific identities of Mr. Ulrich. Honestly, judging 
from the facial and structural features of his figures, it appears to me 
that it would be more advantageous to science if we also set limits, 
in our descriptions, to the ranges of variation in some of our Car- 
boniferous types. In the early daj^s of science certain limitations 
were acknowledged by McCoy in the Palaeozoic Fossils, but since then 
the twenty-six species of Fenestella, admitted by him, have been 
reduced to four or five, and I cannot, so far as I am acquainted with 
the group, revolt against the reduction. 
Family Hyphasmoporid/e, Vine. 
1885. Family Hyphasmoporidse (?) Provisional, Proc. Yorks. Geol. 
and Polyt. Soc, vol. ix. 
