Frof. H. A. Nicholson — On a Netv Tabulate Coral. 253 



List of species occurring in the Cow Stones of the coast section in 

 West Dorset, and not occurring in the Gault of the same : 



Fodopilumniis Fittoni, M'Coy. 

 Necrocarcinus Bechei, Desh. 

 Hoploparia longimana, Sby. 

 Cardium gentianum, Sby. 

 Lucina pisum (?), Sby. 

 Modiola, n. sp. 

 Lima semisulcata. 

 L. Bupiniana, D'Orb. 

 Thetis Soiverbyi, Eora. 

 Trigonia alceformis, Park. 



Trigonia scabra, Lam. 

 Cytherea plana, Sby. 

 Cucullcea glabra, Park. 

 Myacites gurgites, Goldf. 

 Venus immersa, Sby. 

 Tellina incequalis, Sby. 

 Turritella granulata, Sby. 

 Fleuroiomaria Bhodani, D'Orb. 

 Ichthyosaurus campyhdon, Carter,) 

 West of Lyme Regis./ 



III. — On Columnopoka, a New Genus of Tabulate Corals. 



By H. Alleyne Nicholson, M.D., D.Sc, F.RS.E., 

 Professor of Natural History in University College, Toronto. 



Genus Columnopoka, Nicholson. 



Gen. Char: — Corallum aggregate, massive, comj)osed of hexagonal 

 corallites, which have distinct walls, but are firmly united with one 

 another. Septa well developed and close-set, but short and not 

 nearly reaching the centre of the theca. A row of large and closelv- 

 approximated mural pores between each pair of septa. Tabulse 

 horizontal, not vesicular or infundibuliform, apparently incomplete. 

 Epitheca u.nknown. No coenoenchyma. 



I have established this genus for the reception of a single species 

 of coral, of which I have seen two well-preserved examples — one 

 collected from the Hudson River Group of Canada by Mr. George 

 Jennings Hinde ; the other obtained from the Cincinnati Group 

 (Hudson Eiver Formation) by Mr. U. P. James. The genus Column- 

 opora is intermediate in its characters between Favosites and 

 Columnaria, both of which it resembles in its general form, its pi'is- 

 matic closely-approximated corallites, and the absence of a distinct 

 coencenchyma. The genus further resembles Favosites in possessing 

 mural pores, but it is distinguished from the latter by the possession 

 of very distinct and well-marked septa, and by the fact that the 

 mural pores are arranged in very numerous rows, and are of very 

 large size, so that the walls of the corallites have a regularly cribri- 

 form aspect. The genus agrees with Columnaria, Goldfuss, in the 

 possession of distinct septa, but is fundamentally distinguished by 

 the perforated walls of the corallites. There is no other genus, save 

 the above-mentioned, to which Golumnopora is allied with sufficient 

 closeness to render it necessary to institute any explicit or detailed 

 comparison. 



The following are the characters of the only species of the genus 

 known to me : — 



COLUMNOPORA CRIBRIFORMIS, Nich. 



Spec. Char. — Corallites for the most part hexagonal or pentagonal, 

 averaging about one line and a half in diameter, sometimes more or 

 less. Septa in the form of strong vertical ridges, from twenty to 

 twenty-four in number, equally developed, never reaching the centre, 

 or extending more than quite a short distance into the interior of the 



