Geological Society. 145 
of orthoclase, grains of quartz, a few needle-like crystals of horn- 
blende, and a little chlorite, all of which are set in a felsite paste. 
With a high power the grains of quartz are seen to contain nume- 
rous gas-cavities, remarkable for their angular and crystalline forms ; 
others contain a fluid, and show a small bubble. Prof. Hull ex- 
plained. the supposed origin of this remarkable rock, as having 
been the consolidated core of an ancient volcano, from which the 
loose materials, originally forming the sides of the voleanic cone, 
had been stripped off by denudation, thus leaving the solid core 
standing alone, 
Staurastrum mesoleium, n. s., evhibited —Mr. Archer drew atten- 
tion to a Staurastrum form, which, though not quite peculiar to 
Callery Bog, seems to have its headquarters there. He had once or 
twice seen it from Connemara, and he suspected it may probably be the 
same as aform mentioned by Mr. Roy as having been found at Scor- 
ston Moor, near Aberdeen ; but Mr. Archer had never seen examples 
from there. Mr. Roy had suspected his form, at any rate, to come 
near to Staurastrum oligacanthwm, non Bréb., but as once under- 
stood by Herr Nordstedt; but the latter, as he since acknowledged, 
is wholly a different thing from St. oligacanthum, Bréb. (rare enough 
in Ireland), and he had proposed to name the Swedish form Stawr- 
astrum medioleve. But the Callery form (and possibly, as men- 
tioned, the Aberdeen form too) seems to be, indeed, altogether 
different from the Swedish form, now to be known as St. medioleve, 
Nordstedt. The Callery form is a pretty one, about medium-sized, 
triangular in end view, in front view the angles a little produced, 
slightly spinulose. From its resemblance (albeit distant) to, and its 
association, for the time being, in our ideas, with the Swedish form 
(although neither name appears very appropriate), Mr. Archer 
would propose to designate the present form by the (companion) 
name Staurastrum mesoleium. 
GEOLOGICAL SOCIETY. 
December 19, 1883.—J. W. Hulke, Esq., F.R.S., 
President, in the Chair. 
The following communication was read :— 
““On some Remains of Fossil Fishes from the Yoredale Series 
at Leyburn in Wensleydale.” By James W. Davis, Esq., F.G.S. 
After describing the nature and succession of beds among the 
rocks which yielded the fossils under consideration, the author dis- 
cussed the conditions under which they were deposited. He pointed 
out that the Fish-fauna of the Yoredale series was distinguished by 
some important peculiarities from that of the Mountain Limestone 
below, as also from that of the Coal-measures. Some of the Car- 
