GEOLOGY. 



311 



length and probable number of the vertebrae as the scale, although we 

 should have a reptile of relatively abbreviated proportions, yet in this 

 case the original creature would surpass in magnitude the most co- 

 lossal of reptilian forms. In this connection Dr. Mantell offers some 

 comments on the probable physical condition of the countries inhabited 

 by the terrestrial reptiles of the secondary ages of geology. The high- 

 ly organized land saurians appear to have occupied the same position 

 in those ancient faunas, as the large Mammalia in those of modern 

 times. The trees and plants whose remains are associated with the 

 fossil bones manifest, by their close affinity to living types, that the 

 islands or continents on which they grew possessed as pure an atmos- 

 phere, as high a temperature, and as unclouded skies, as those of our 

 tropical climes. There are, therefore, no legitimate grounds for the 

 hypothesis in which some physiologists have indulged, that during the 

 "Age of Reptiles" the earth was in the state of a half-finished 

 planet, and its atmosphere too heavy, from the excess of carbon, for 

 the respiration of warm-blooded animals. Such an opinion can only 

 have originated from a partial view of all the phenomena which these 

 problems embrace ; for there is as great a discrepancy between the 

 existing faunas of different regions, as in the extinct groups of animals 

 and plants which geological researches have revealed. Sim-mail's 

 Journal, May. 



FOSSIL TURTLES. 



A REMARKABLY fine chelonite, by far the most perfect specimen of 

 the kind ever found in the Purbeck beds, has been discovered in the 

 newly-constructed Feather Quarry. The two portions of the shield 

 of the turtle are situated side by side, and the carapace, or upper 

 shield, presents its superior surface to view. It is perfect, with the 

 exception of the posterior neural, and one costal plate ; it is 15k inches 

 long, and 1U broad. The plastron, or under shield, is less perfect, 

 being defective at the anterior and right lateral portions ; it is 13 

 inches long, and 11-i broad. But what is remarkable, the under or 

 inferior surface is uppermost on the stone, whilst the carapace pre- 

 sents the upper or superior surface, which renders it doubtful whether 

 the two portions belonged to the same individual or not, although the 

 dimensions of both perfectly correspond. The specimen might, in 

 all probability, be referred to the genus Emys, but the species does 

 not appear to have been hitherto known, as it is totally different from 

 any described by Professors Owen and Bell, in their Monograph on 

 Fossil Reptilia. London Mining Journal, July 20. 



Among the casts of a set of Himalaya fossils recently presented to 

 the Boston Society of Natural History by the British East India Com- 

 pany, were a cranium, humerus, and parts of the sternum of Colosso- 

 chelys Atlas, which must have been of an immense size. With refer- 

 ence to this, Prof. Agassiz observed, that he had found at Philadelphia 

 a femur of a gigantic turtle, taken from the green-sand of New Jer- 

 sey, which he thinks must have been larger than the Himalaya spe- 

 cies, judging from the size of the femur, which was larger than that 



