TOMES : MESOZOIC CORALS OF THE COUNTY OF YORK. 
75 
examining, commencing with the Liassic species, and proceeding 
upwards to those of the later formations. 
I. — Liassic species. 
Heterastr^ea excavata Fromentel sp. 
SeptastrcEa excavata E. de From., in Martin Infra Lias, 
Cote d'Or, 1860. 
Septastrcea excavata Blake. Yorkshire Lias, p. 447, 1876. 
The genus Septastroia of D'Orbigny having undergone a very 
searching examination by Dr. Hinde,* can no longer be admitted 
as a British or even a European genus. It is an American 
form, and confined to the Tertiary formation. In the Geological 
Magazine of May, 1888,t the present writer showed that all the 
British species of Septastroia possessed characters which were 
wholly inconsistent with those of that genus, and created for 
their reception a new genus, which was designated Heterastrcea. 
The necessity for such a genus was obvious, and has been con- 
firmed by the discovery of a considerable number of new species. 
Montlivaltia polymorpha Terquer et Piette. 
Montlivaltia polymoiyha Terq. et Piette. Lias Inf. de 
I'Este de la France. PI. XVL, Figs. 17-21. 1865. 
As a Yorkshire species the present appears to be rare, only 
eight examples being recorded by the Rev. J. F. Blake in 1876.| 
It was included by the late Professor Duncan in the list of 
madreporaria from the South Wales conglomerates, but, as I have 
elsewhere shown, § the specimens from that locality were really 
nothing more than fragments of a species of Thecosmilia. 
Up to the present time I believe Montlivaltia polymorjyha, 
as a British species, is confined to Yorkshire, from which locality 
I have examined specimens. 
* Quart. Journ. Geol. Soc, Vol. XLIV., p. 200, 1888. 
t Decade IIL, Vol. V., p. 215. 1888. 
% Yorkshire Lias, page 447. 1876. 
§ Quart. Journ. Geol. Soc, Vol. XL., p. 365. 1884. 
