PROCEEDINGS UP GEOLOGICAL SOCIETIES. 



213 



(.umbines Chelonian with Lacertian characters. Transmitted by ]Mr. Eain from 

 South Africa. 



Dici/nodon tigriceps. — Pelvis : Ihum, ischium, and pubis coalesced to form an 

 OS innominatimi, with the suture at the symphysis obhterated. At least live 

 sacral vertebn^, the first with a broad, thick, triangular, terminally expanded 

 pleurapophysis. The strong, straight, trihedral iluim overhes the above sacral 

 rib, and extends forward to overlie also the last long and slender rib of the free 

 tnmk (thoracic) vertebras. There are no lumbar vertebife. 



Pubis very thick, strong, with a broad inferior convexity resembling that of the 

 Mon 'dor in its internal perforation and external apophysis ; ischium receiving the 

 abutment of the last two pahs of sacral vertebrae. 



The form of the anterior aperture of the pelvis is oval, with the sides broken by 

 a slight angle at the middle, and the small end encroached upon by the right 

 angular preminence of the symphysis pubis. 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 this aperture is bounded by the fii'st sacral vertebra exclusively, 

 at the middle by its centnmi, at the sides by its ribs ; the hind-half of the 

 aperture is boimded by the pubic bones. From the penultimate sacral vertebra 

 to the s}inphysis pubis it measm-es 5 mches. 



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 Africa. 



Crocodilia (?). Genus Massospondylns, Ow. (Gr. iJ.a<T<TMu, longer ; a-nouSvXos 

 vertebra). — The author exliibited diagTams, and pointed out tlie characters on 

 which he had founded (in the Catalogue of Fossil Remains of the jNIuseum of the 

 College of Surgeons) the genus Massospondylus, exemplified by the M. carinatus. 



Genus Pachyspondylus, Ow. (Gr. Traxus, thick ; o-ttoz'SuAus, vertebra.) — The 

 fossils exemplifying tliis genus form part of the same collection, obtained by 

 Messrs. Orpen from sandstones of the Drabenberg range of hills, South Africa, 

 and presented to the College of Surgeons. 



2. "On the South-easterly Attenuation of the Lower Secondary Rocks of 

 England, and the probable depth of the Coal-formation under Oxford and North- 

 amptonshire." By Edward Huh, Esq., A.B., F.G.S. 



By a series of comparative sections, made by actual admeasurements by the 

 ofiicers of the Geological Survey, it was shovv^i that all the Lower Secondary 

 formations attain their gTeatest development towards the north-west of England, 

 and, on the other hand, they become attenuated, and in some cases actually die 

 out in the opposite direction. For example, it was shown tliat the Bunter Sand- 

 stone in Cheshire reaches a thickness of 2,000 feet, in Staftbrdshire 600, and in 

 East Warwickshire is absent ; and a similar law of soutli-easterly attenuation was 

 shown to maintain in the case of the Keuper, Lias, Inferior Oohte, and lower zone 

 of the Great Oohte. 



It was sho^Mi 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 fact of its occm-rence in the Bas-Boulonnais below the 

 Chalk, and resting on Carboniferous rocks, the author infeiTed that it extends more 

 or less unintemiptedly from England to France and Belgium, and southward to 

 Mr. Godwin- Austen's palaeozoic axis. The cause of this superior degree of per- 

 sistency was refen-ed to the organic, as distinct fi'om the sedimentary nature of the 

 formation, and its accumulation (like the White Chalk) on a deep sea-bed 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 country stretching west and east fi^om 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 the Old Red and Silurian lands by which they Avere surrounded, was 

 insisted upon, and especially as agTeeing with the observations of Murchison, 

 Ramsay, and other authors. 



VOL. II. 



R 



