56 report — 1865. 



from the absorption of water, the specific gravity diminishes, and may descend to 

 263 or 2-55. 



The internal columnar structure and the peculiar concentric -weathering of these 

 rocks have also been the subject of special study, and the results of the observa- 

 tions made lead quite to disprove the evidence of any so-called globular structure 

 in these rock-masses, but to prove that the columnar or so-called basaltic structure 

 is due merely to mechanical cajises, i. e., the cooling of masses possessing a nearly 

 homogeneous structure and subjected to the pressure of the surrounding or overlying 

 strata ; and that the development of this columnar structure is in proportion as the 

 rock is more fine-grained and less crystalline, or in other words more homogeneous. 

 The sedimentary strata in contact are themselves frequently so altered by contact 

 with the igneous rocks as to present in themselves a columnar structure or jointing, 

 in some cases quite or even more perfect than the igneous rock itself ; and a bed 

 of clay-ironstone at Pouk Hill was found jointed into regular hexagonal columns by 

 the heating and the subsequent cooling and contraction due to the proximity to 

 the igneous rocks which form the basis of Pouk Hill. 



On a New Wealden Saurian named Polacanthus. By the Rev. W. Pox. 



The author had discovered in the Wealden beds of the Isle of Wight, between 

 Black Gang and Brooke, a new reptile of the Dinosaurian family. The only parts 

 of the skeleton wanting are the head and neck. The animal was above C feet long 

 from the shoulder to the sacrum, and was furnished with a massive tail 5 feet long. 

 The legs were about 4 feet in length, terminating in broad short feet. This strange 

 reptile was clothed with long armour-plates of bone, from A an inch to 4 inches in 

 diameter, and about i an inch thick, that covered its body, with the exception of 

 its back, which was protected by a great bony shield. Another remarkable cha- 

 racteristic of this animal was a process of spine-like bones which ran along the sides 

 of the body and tail, some of which are 15 inches long, and in weight 7 lbs. The 

 remains of this fossil, as well as the Wealden formation from which they were ex- 

 tracted, were examined recently by Professor Owen ; and with reference to the 

 extraordinary nature of the spine-like bones, Professor Owen is of opinion that the 

 most appropriate name for this new Saurian would be Polacanthus. 



On the Progress of the Imperial Geolor/iccd Institute of the Austrian Emjn'rc. 



By W. von Haidingeb. 



A concise history of the Imperial Geological Institute was given by the Director 

 in the opening address of the 8th of November, 1864, comprehending fifteen years 

 since its foundation in 1849, during the reign of the present Emperor, Francis 

 Joseph I. During this time, the geological explorations of the country have gra- 

 dually proceeded, so that 155 sheets of the Austrian Ordnance maps have been geo- 

 logicallv coloured, 110 of them in the scale of 1 : 144000 (about 2^ miles to an inch), 

 and 45 'in the scales of 1 :288-000 and 1 : 432-000 (nearly 4| and 7 miles to an inch), 

 comprising, to more or less detail, all the provinces of the whole empire. Thirteen 

 volumes of the Jahrbuch (Annals in 8vo) have been published, as also three volumes 

 of Memoirs in 4to. Of the copies printed (1000 and 600), no less than 800 and 340 

 respectively are gratuitously distributed. A library is formed, containing more than 

 13,000 volumes, also a considerable collection of maps, including nearly 4000 sec- 

 tions. The comprehensive collections of minerals, rocks, and fossils are open to 

 public inspection in twelve rooms of the Prince Lichtenstein's palace, rented by 

 Government for the Geological Institute. 



During the year 1804, moreover, an additional set of seven sheets of maps of the 

 north-west of Hungary was completed, as also six sheets thoroughly revised of the 

 difficult region of the sedimentary secondary rock of the north-eastern Alps. 



The geologists of the Institute were again at work in the north-west of Hungary, 

 proceeding from the sections gained the summer before in the direction towards 

 the east. The whole of the classical country around the ancient mining centre of 

 Schemnitz was this time the object of exploration. Among other interesting facts, 

 it was ascertained that the metalliferous greenstone-trachyte was superincumbent 

 on slates of the Werfen series, with Myacifcs fassaensis, Posidvnomya Clara, &c. 



