VINE : NOTES OX YOREDALE POLYZOA. 
83 
Genus Diplopora, Young & Young. 
,, Acantiiopora, Young & Young. 
,, Actinostoma, Young &, Young. 
It is to this group that ]\[r. A. W. Waters refers in his paper on 
Cyclostomatons Bryozoa (Quart. Jour. Geol. Soc, Nov., 1884, 
p. 675), when speaking of Palasozoic species, and he suggests that 
probably this peculiar structure may represent the sub-oral pore 
and avicularium, and as long as we do not know the signification of 
the adventitious tubles of Diastopora obelia, &c., we ma}^ be justified 
in asking if they may not possibly have had an homologous origin." 
15. Diplopora margixalis, Young & Young. 
= Glauconome (Diplopora) id., Y. & Y., Proc. Nat. Hist. Soc, 
Glasgow, 1875, pi. TIL, figs. 14-21. 
= Glauconome id., Vine, Proc. York. Geol. Soc, 1881, p. 333. 
Pinnatopora id., Vine, Fourth Brit. Assoc. Rep., 1883; Natuialist, 
1884-5. 
Zoarium erect, slender, branching at intervals but without 
pinnee. Zocmia orifice circular (normal), alternate and marginal 
which gives a serated outline to the branch — about twenty-four 
or twenty-six to quarter of inch. On either side of the branch 
beneath the Zoaecia there is a small secondar^^ pore, which is 
separated from the larger opening by a delicate septum; if the 
septum is broken, the Zoaecia (abnormal) is apparently pyriform. 
Carina : (Mesial) a delicate tuberculated keel separates the two rows 
of marginal Zosecia. Besides the mesial keel there are others — 
generally one on either side, Reverse finely tuberculated in parallel, 
longitudinal ridges. 
Zoca^i^ies; Yoredale; Gleaston Castle. Hurst, Yorksh. Rather 
widely distributed in the Lower and Upper Scotch shales. 
This is one of the most delicate Polyzoa of the Carboniferous 
shales, and though rather widely distributed, it is not what may be 
called a common form in the Upper Shales. There is, however, in 
some of the more robust examples (often met with in the Yoredale 
rocks), a slight change in the general aspect of the cell, so much so 
that at times it is very difiicult to identify the Upper Carboniferous 
with Lower Carboniferous forms. In the Lower Scotch Shales, 
