Geological Society. 69 
tem, unless it be the so-called Volborth’s organ. Buerocrinus is 
probably to be regarded as a permanent larval form, which has 
only developed arms on three of its radials. 
Hybocystites problematicus, from the Lower Silurian of Kentucky, 
which is supposed by Wetherby to be an intermediate form between 
the Crinoids and the Cystids, is believed by the author to be more 
closely allied to the Blastoids than to the Cystids. The three so- 
called arms are merely upward prolongations of the radials, which 
are segmented in the same way as the downward extending radials 
are in Pentacrinus briareus. They are not arms like those of 
Hybocrimus and other Crinoids. Of the five ambulacra that diverge 
from the peristome, the right and left anterior ones pass directly 
downwards from the summit onto the corresponding radials, and 
thence onto the basals. The other three ascend the inner faces 
of the short radial extensions, pass over their tops and down their 
outer faces, where they have been described as ‘more or less obscure 
furrows, of which nothing further is known.” In some cases they 
reach the basals, and in others not, exhibiting a considerable amount 
of variation both in this and in other respects. There are therefore 
five recurrent and appressed ambulacra, and not two only, together 
with three arms, like those of Crinoids. 
2. “On the Madreporaria of the Inferior Oolite of the Neigh- 
bourhood of Cheltenham and Gloucester.” By R. F. Tomes, Esq., 
F.G.S. 
The author called attention to the observations of Milaschewitsch 
on ‘* Rejuvenescence”’ in corals, published in vol. xxi. of the Pale- 
ontographica, and explained its nature as opposed to “‘ gemmation.” 
He suggested that, in describing corals, the following classification 
of the costz should be adopted :-— 
1. Mural coste=those which appear on the wall, whether of 
simple or compound species. 
2. Septal coste =those which are a prolongation of the septa. 
3. Intercalicular coste=those which cover the ccenenchyma be- 
tween the calices. 
He adopted in general Dr. Wright’s views as to the stratigraphical 
position of the coralligenous deposits in the Gloucestershire Inferior 
Oolite, and gave a tabular statement of the distribution of the 
species in the several coral-beds, pointing out that each of these has 
its own species, which do not pass much from one to the other. He 
recorded about sixty species, many of which were described as new, 
and proposed two new genera (Phyllogyra and Phylloseris), besides 
introducing five or six genera previously characterized on the con- 
tinent, but not recognized in England—namely Donacosmilia, Con- 
fusastrea, Chorisastreea, Oroseris, and Dimorpharea. 
The author referred especially to some so-called Thecosmilie, such 
as -7’. gregaria, and insisted that they should be removed to the 
genus Chorisastr@a, aS they increase by gemmation at the base 
