Geological Society of London. 281 



the ischium there is a posterior process which united with the ilium 

 and formed the posterior boundary of the acetabulum, the inner 

 border of this and the posterior part of the proximal surface of the 

 pubis forming a common curve belonging to the acetabulum. The 

 author campared the arrangement with that found in Atlantosaurus 

 immanis, Marsh. 



3. " On Neusticosaurns piisillus (Fraas), an Amphibious Eeptile 

 having Affinities with the Terrestrial Nothosauria and with the Marine 

 Plesiosauria." By Prof. H. G. Seeley, F.R.S., F.G.S. 



These remains come from the Lettenkohle, a stratum between the 

 Upper Muschelkalk and Keuper, and were obtained at Hoheneck, 

 about nine miles north of Stuttgart. They have been already noticed 

 by Dr. Fraas under the name of Simosaurus piisiUus ; but the palate 

 differs much from that of this genus, and from all others that are 

 known. Neusticosaurus is the smallest representative of the Plesio- 

 sauria yet known, and has a special interest as exhibiting hind limbs 

 with the characteristics of a terrestrial animal, while the fore limbs 

 are modified into paddles. Two specimens have been obtained. 

 The extreme length of the skeleton of the larger is about 270 millms., 

 and, with the exception of the abdominal ribs and some parts of the 

 pelvic girdle, it is perfect. The author describes minutely the 

 various parts of the skeleton, concluding with some remarks on the 

 affinities of the Crocodiles with the Plesiosaurs. Neusticosaurus in- 

 dicates that the latter had ancestors which were terrestrial in habit. 



11— April 5, 1882.— J. W. Hulke, Esq., F.R.S., President, in the 

 Chair. — The following communications were read : — 



1. " Geological Age of the Taconic System." By Prof. J. D. 

 Dana, F.M.G.S. 



The author takes exception to some remarks made before the 

 Geological Society by Dr. T. Sterry Hunt on the IGth November 

 last. Dr. Sterry Hunt has thrown doubt on the results arrived at 

 by the geologists who have studied the relations of the so-called 

 Taconic strata, not in consequence of any observations of his own, 

 but on the general ground that " where newer strata are in uncon- 

 formable contact with older ones, the etfect of lateral movements 

 of compression, involving the two series, is generally to cause the 

 newer and more yielding strata to dip towards, and even beneath 

 the edge of the older rock — a result due to folds, often with inversion, 

 sometimes passing into faults." 



It was pointed out in opposition to these views, that the observa- 

 tions of Emmons, H. D. and W. B. Eogers, Mather, Sir W. Logan, 

 James Hall, E. Hitchcock, C. H, Hitchcock, Hager, and Wing, 

 prove that the Taconic schists and limestones are in conformable 

 succession and of Silurian age. The stratigraphical structui'e of the 

 Taconic range is, indeed, so simple that all observers who have 

 studied it have described the schists and limestones as conformable ; 

 and numerous characteristic Silurian fossils have been found in 

 both. This view had been maintained by Sterry Hunt himself till 

 1878, when he fi.rst propounded his new interpretations of the strata 



