PRITISn ASSOCIATION MEETING. 
485 
Absinact, of a, Paper " On some Fishes and Tracks from the Passage- 
rocks, an'd from the Lower Red Sajjdstone of IIereeordsiiire." 15y 
THE Rev. W. S. Symonhs, F.G.S. 
Mr. Syinoiuls, in tliis paper, called upon Sir Roderick Murchison to make 
greater allowances tliau he had hitiicrto seemed dis]M)sed to do for Ihe appear- 
ance of fish in the Lower liudlow rocks of Leiutwardine, Herefordshire. This 
fish, tlie P/cm.yti.i L/cc//'/ix/-i (Salter), was not found as Sir R March ison seemed 
disposed to regard its discovery, in strata a few feet below the original nppcr 
Ludlow "bonc-bed," but in the Lower Ludlow deposits, with the whole thick- 
ness of the Upper Lndlow shales and Aymestry rock intervening. Tlierc was 
no doubt of the fact that fisli-lifcmnst now be iinmeusely ante-dated, even since 
the publication of Sir R. Mureliison's last ciition of liis work upon Siluria. 
Mr. Symonds called the attention of the audience to a collection of fossils 
showing the gradation of the Pteraspis from the Lower Ludlow rocks, through 
those passage- or transition-rocks which lie between the upper Silurians and the 
Old Red sandstone, into the central Old Red rocks of llcrefordshire. The 
species were different, but the genus was the same. Stereoscopic plates were 
exhibited of a large slab of Old Red sandstone wliich was ri])pled by the waves 
of the ancient Old Red sea, and scored deeiily by some Old Red fisli or crus- 
tacean which had wended its way over a shallow beach or sandy shore. The 
slab was obt.ained by the late Rev. T. T. Lewis of Aymestry, the friend and 
coadjutor of Sir R. 1. Murcliisou, and who at his death left it to Mr. Symonds. 
On the Okigin of the Structure called Cone-in-Cone, by H. C- 
SoRBY, r.R.S., &c. 
Coue in Cone is met with in so many stratified rocks, that most geologists 
must be familiar with its general characters. No one, however, appears to 
have thoroughly investigated it ; or to have given any very satisfactory explana- 
tion of its origin. The cones often occur in bands parallel to the stratification 
of the rock, their apices starting from a well defined plane ; and, after extending 
upwards or downwards for a greater or less distance, with their axes perpen- 
dicidar to the plane of stratification, they end in bases parallel to the stratiii- 
catiou, but not all at the same exact level. They are not perfect cones, but 
are of such forms as would result from the varied interference of surrounding 
cones, and from the development of others ^Aitliin their own substance. On 
examining thin, transparent sections with a low magnifying power, under polar- 
ized Hght, the author had been able to ascertain that tliis peculiar structure is 
intimately connected with some kinds of oolitic grains. In the formation of 
oolitic grains small prismatic crystals were deposited round a centre-nucleus, 
radiating to all sides in nearly the same amount, so as to give rise to irregular 
ovoid bodies ; whereas, in the formation of cone in cone, very similar crystals 
were deposited almost entirely on one side, along the line of the axes of the 
cones, in such a fan-shaped manner as to give rise to their conical shape. In 
the thin sections of some specimens prepared for examination, every connecting 
link between imperfect oolitic grains and genuine cones can be seen to great 
advantage with polarized Light. The growth of the cones did not, however, 
proceed without interruption, for other smaller fan-shaped groups were developed 
within the larger ; and thus by the mutual interference of contiguous groups 
and of others contained witliin themselves, there was formed a mass of irregular 
cones Lnclosmg other cones. We must therefore conclude that this structure 
is one of the peculiar forms produced by concretiouai'j crystalization after the 
deposition of the rock. 
VOL. 11. 
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