TOMES : MESOZOIC CORALS OF THE COUNTY OF YORK. 
77 
The basal wall is nearly horizontal, star shaped, and has 
six points, which are the lower terminations of the prominent 
angles. It is naked and costulated, and the costee are continuous 
with the later cycles of septa, but not with the primary ones. 
There are dissepiments connecting the costa?. 
There is a small apical fossula. The margins of the septa 
are entire, and their sides are smooth. There is no synapticular 
growth of any kind. 
In the course of the investigations which have led to the 
above definition of the genus, considerable doubt arose as to 
whether the whole of the upper surface is calicular, or whether 
that part is confined to the apical fossula. I conclude, however, 
that Professor Duncan very rightly regarded the whole of the 
upper part of the corallum as calicular, and for the following 
reason :— The prominent angles have between them what must 
be taken as true septa, because in relative height they correspond 
with the normal development of the cycles in certain of the 
Astrceidce. Sometimes Montlivaltia lens is so much elevated as to 
be almost dome shaped, and the cycles very closely resemble the 
c\'cles in Gonioseris. I am entirely, therefore, in accordance 
with the original describer in believing that the whole of the 
upper surface of the corallum in Gonioseris is calicular, though 
I difier widely from him as regards the affinities of the genus. 
It is in the comparative lateral prominence of the cycles that 
the form presents such an anomaly, the septa of the second cycle 
being in the receding angles have much less prominence than 
those of the third and fourth. Gonioseris is certainly a genus 
of the Astrceidce. 
Gonioseris Leckenbyi Dune. 
Gonioseris Leckenhyi Dune. Sup. Brit. Fos. Cor., pt. iii., 
p. 22, pi. vii., figs. 6-9. 1872. 
Of the two species of Gonioseris described by Prof. Duncan 
the present is much the more t}'pical, and a somewhat detailed 
description of it is desirable. There are some specific peculiarities 
which escaped the notice of the original describer, namely, the 
