PROCKEDINGS UP GEOLOGICAL SOCIETIES. 
213 
combines Chelouian witli Laccrtian characters. Transmitted by Mr. Bain from 
South Africa. 
Dii-ynodon tigriceps. — Pelvis : IHmn, ischiiun, and pul)is coalesced to form an 
OS innominatum, with the suture at the symphysis obliterated. At least five 
sacral vcrtcbnv, the fii-st with a broad, tliick, triangidar, terminally expanded 
jdetirapoiihysis. The strong, straight, trihedral iluim overlies the above sacral 
rib, and extends forward to overlie also the last long and slender rib of the free 
trunk (thoracic) vertebra;. There are no luml)ar vertebra;. 
Puliis very thick, strong, with a broad inferior convexity resembling that of the 
Monitor in its internal perforation and external apophysis ; ischium receiving the 
abutment of the last two pairs of sacral vertebnie. 
The form of the anterior aperture of the jielvis is oval, with the sides broken by 
a slight angle at the middle, and the small end encroached upon by the right 
angular prominence of the symphysis jiubis. The long diameter is 11 inches (from 
the fore-end of the first sacral vertebra), the transverse diameter is 10 inches. 
The fore-half of tliis aperture is bounded by the first sacral vertebra exclusively, 
at tlie midtlle by its centnun, at tlie sides Ijy its ribs ; the hind-half of the 
aperture is bounded by the pubic bones. Froni the penultimate sacral vertebra 
to the symphysis pubis it measm'es 5 inches. 
The outlet of the pelvis is of a semi-elliptic form, 9 inches in transverse, and 4 
inches in the opposite diameter. Original transmitted by Mr. Bain fi'om East 
Brink River, South Aft-ica. 
Crocodilia (?). Genus Massospondylus, Ow. (Gr. ixaaaav, longer ; citovSvKos 
vertebra). — The author exhibited diagrams, and pointed out the characters on 
whicli he had founded (in the Catalogue of Fossil Remains of the Museum of the 
College of Surgeons) the genus Massospondylus, exemplified by the M. carinatus. 
Genus Pachyspondyhis, Ow. (Gr. iraxvs, thick ; (riroi'SvXvs, vertebra.) — The 
fossils exemi>lifyiiig tliis genus form part of the same collection, obtained by 
Messrs. Orpen from sandstones of the Drabenberg range of hills, South Afiica, 
and presented to the College of Surgeons. 
2. "Ou the South-easterly Attenuation of the Lower Secondary Rocks of 
England, and the probable depth of the Coal-formation under Oxford and North- 
anrptonshire." By Edward Hidl, Esq., A.B., P.G.S. 
By a series of comparative sections, made by actual admeasurements by tlie 
officers of the Geological Survey, it was showni that all the Lower Secondary 
formations attain their greatest development towards the north-west of England, 
and, on the other hand, they become attenuated, and in some cases actually die 
out in the opjiosite direction. For example, it was shown that the Bunter Sand- 
stone in Cheshire reaches a thickness of 2,000 feet, in Staffordshire 600, and in 
East Warwickshire is absent ; and a similar law of south-easterly attenuation was 
shown to maintain in the case of the Keuper, Lias, Inferior Oohte, and lower zone 
of the Great Oolite. 
It was shown that the upper zone of the Great Oolite (the White and Grey 
Limestones of Wilts, Oxford, Lincoln, and Yorkshire,) forms the first exception 
to the law ; and from the fiict of its occurrence in the Bas-Boulonnais below the 
Chalk, and resting on Carboniferous rocks, the author inferred that it extends more 
or less unintennptedly from England to France and Belgium, and southward to 
Mr. Godwin-Austen's paleozoic axis. The cause of this superior degree of per- 
sistency was referred to the organic, as distinct from the sedimentary nature of the 
formation, and its accumulation (hke the White Chalk) on a deep searbed by the 
agency of Molluscs, Corals, and Foraminifera. 
It was shown that the Lower Permian beds are scarcely represented in Lancashire 
and North Cheshire, but that they attain their greatest development (1,800 feet) 
along a band of coimtry stretching west and east from Salop to Warwickshire, 
and the author traced the margin of the basin in which they were formed along 
the west, north, and east. The local origin of these Permian beds, as having been 
derived from tlie Old Red and Sihu-ian lands l)y which they Avere surrounded, was 
insisted upon, and especially as agreeing with the observations of Murchison, 
Ramsay, and otiier authors. 
VOL. 11. 
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