Geological Society. 59 
do not show any signs of attrition. They must, however, be the 
result of the disintegration of older rocks, or the genera which they 
represent existed to a much later period than is generally supposed. 
The following new species were described :—Ctenoptychius Ordu ; 
Nemacanthus filifer, Ag., varieties a and /; Nemacanthus nunor ; 
Sphenonchus obtusus ; Hybodus austinensis and pustulosus ; Petalodus? 
2. “On some Fish-spines from the Coal-measures.” By J. W. 
Davis, Hsq., F.S.A., F.G.S. 
The author described in this paper three species of a new genus 
of fossil fish from the Carboniferous formation, two of the species 
having been found in the Cannel Coal of the West Riding of York- 
shire, and the other in the Burghlea limestone, near Edinburgh. 
Anodontacanthus is a straight spine, offering many points of resem- 
blance to some of the Pleuracanths: it has a similarly close-grained 
microscopical structure ; the internal cavity opens terminally at the 
base of the spine; and it was not deeply implanted in the flesh of 
the fish. It, however, differs from all the Pleuracanths in being 
quite free from external denticles; its surface is plain or but 
slightly striated; whilst that of Plewracanthus always possesses a 
double row of denticles, either ranged laterally along the exposed 
part of the spine or in some position between the lateral and pos- 
terior aspects of the spine. It is possible that evidence may be 
discovered which will render necessary the removal of these spines 
to the genus Plewracanthus; but at present there is no evidence that 
such is advisable. All the specimens of Plewracanthus-spine found 
associated with teeth or shagreen have been armed with the double 
row of denticles; and at present no evidence exists that spines 
without denticles were associated with remains of this genus. It 
is therefore considered best to institute a new genus for the three 
species, with the name Anodontacanthus, in allusion to its having no 
teeth or denticles. 
3. “On some Specimens of Diastopora and Stomatopora from 
the Wenlock Limestone.” By Francis D. Longe, Esq., F.G.S. 
Mr. Longe showed and described some specimens of Bryozoa from 
the Wenlock Limestone of Dudley, which he compared with corre- 
sponding forms from the Oolite and later periods, and pointed out 
the close similarity of the Silurian with the later forms, in respect 
of the shape and dimensions of the cells, as well as in the habit of 
coencecic growth. 
Alluding to some other Paleozoic forms, assigned to the Bryozoa 
under the generic names of Berenicea and Ceramopora, he pointed 
out the difference between the shape of the cells in these forms and 
those which he had described, and expressed a doubt whether they 
should be classed as Bryozoa at all. 
On the other hand he referred to some specimens described by 
Professor Nicholson (Ann. & Mag. Nat. Hist. vol. xv., 1875) under 
the names of Alecto auloporoides &e., as having the true Bryozoan 
