Geological Society of London. 141 
the strata of Greenland or Spitzbergen, Nordenskjéld maintains 
that there were no glacial conditions there down to the termination 
of the Miocene period. The author maintained that glaciation is 
the normal condition of polar regions, and if these at any time were 
free from ice, it could only arise from exceptional circumstances, 
such as a peculiar distribution of land and water. It was extremely 
improbable that such a state of things could have prevailed during 
the whole of the long period from the Silurian to the close of the 
Tertiary. 
A million years hence it would be difficult to find any trace of 
what we now call the glacial epoch; though if the stratified rocks 
of the Harth’s crust consisted of old land-surfaces, instead of old 
sea-bottoms, traces of many glacial periods might be detected. The 
present land-surface will be entirely destroyed in order to form the 
future sea-bottom. It is only those objects which lie in existing 
sea-bottoms which will remain as monuments of the Post-tertiary 
glacial epoch. Is it, then, probable that the geologist of the future 
will find in the rocks formed out of the non-existing sea-bottom 
more evidence of a glacial epoch during Post-Tertiary times than we 
now do of one, say, during the Miocene, Hocene, or Permian period ? 
Paleontology can afford but little reliable information as to the 
existence of former glacial periods. 
2. “On Remains of Eocene and Mesozoic Chelonia, and on a 
Tooth of (?) Ornithopsis.” By R. Lydekker, Esq., B.A., F.G.S. 
This communication treated in the first place of remains of 
Chelonia from the Cambridge Greensand, Wealden, and London 
Clay. Firstly, Rhinochelys, from the Cambridge Greensand, was 
considered to indicate a Pleurodiran type; and four new specific 
names were proposed, viz. BR. macrorhina, R. brachyrhina, R. Jessoni, 
and R. cantabrigiensis. From the same deposits a skull was 
described which was considered to indicate a new species of Chelone, 
for which the name C. Jessoni was proposed. Other remains of 
marine Chelonians from these beds were regarded as indicating a 
Turtle allied to the Loggerhead, and were provisionally referred to 
the genus Lytoloma, as L. cantabrigiensis. In the course of the 
description, it was proposed to replace the name Huclastes (pre- 
occupied) by Lytoloma. Of other Chelonidz, the new generic name 
Argillochelys was proposed for Chelone cuneiceps, Owen, of the London 
Clay, which would also include some other forms from the same beds. 
A shell of a Plesiochelys from the Wealden of the Isle of Wight was 
regarded as indicating a new species, which was named P. Brodiei. 
It was also shown that Chelone gigas, Owen, of the London 
Clay, did not belong to the Chelonide at all, but indicated a species 
of the genus Psephophorus—a member of the Dermatochelydide. 
The next section of the paper described a peculiar mandibular 
symphysis from the London Clay, which was taken to indicate a 
new genus of Chelonia, to be named Dacochelys; and it was 
suggested that Hmys Delabechei, Owen, might be the same form. 
The paper concluded with a notice of a tooth from the Wealden, 
of the same general type as one previously referred by the author to 
