310 ANNUAL OF SCIENTIFIC DISCOVERY. 



size of the stone, exactly measured from the leaden model, is as fol- 

 lows : Length, 2.48 inches ; greatest breadth, 1.35 inches ; average 

 thickness, 0.92 inch. The actual weight of the diamond is supposed 

 to be 1,108 grains, which is equal to 277 carats of weight of the rough 

 diamond ; but as the rough stones are usually taken to give but one 

 half of their weight when cut and polished, it would allow 1883 carats, 

 or a weight between the Pitt or Regent diamond (13G|) and that of 

 the Grand Duke of Tuscany (139), for it in its present condition. If 

 we take it that one eighth of what it would have been when polished 

 was taken off with the splinter sold to the native, we shall then have 

 155| carats for the possible weight of it, if it had been cut and polish- 

 ed when entire. This would place it in weight between the Tuscan 

 and the great Russian diamond of 195 carats, which last is well known 

 to be an Indian stone. Silliman's Journal, May. 



ON THE PELOROSAURUS, AN UNDESCRIBED GIGANTIC TERRES- 

 TRIAL REFTILE. 



DR. MANTELL, of England, has for a long time entertained the idea, 

 that, among the remains of colossal reptiles obtained from the Wealden 

 strata, there were indications of several genera of terrestrial saurians, 

 besides those established by himself and other geologists. The recent 

 discovery of an enormous arm-bone, or humerus, of an undescribed 

 reptile of the crocodilian type, in a quarry of Tilgate Forest, Sussex, 

 and some remarkable vertebra; not referable to known genera, have 

 induced him to publish the facts which his late researches have 

 brought to light. 



The humerus above mentioned was found imbedded in sandstone, 

 about twenty feet below the surface ; it presents the usual mineralized 

 condition of the fossil bones from the arenaceous strata of the Weal- 

 den. It is four and a half feet in length, and the circumference of its 

 distal extremity is thirty-two inches. It has a medullary cavity three 

 inches in diameter, which at once separates it from marine saurians, 

 while its form and proportions distinguish it from the humerus of the 

 Iguanodon, Megalosaurus, and the like. It approaches most nearly 

 to the crocodilians, but possesses characters distinct from any known 

 fossil genus. Its size is stupendous, far exceeding that of the corre- 

 sponding bone of the gigantic Iguanodon ; the name Pelorosaurus( from 

 TreXcop, monster) is therefore proposed for the genus. No bones have 

 been found in such contiguity with this humerus, as to render it cer- 

 tain that they belonged to the same gigantic reptile ; but several very 

 large caudal vertebrae of peculiar characters, collected from the same 

 quarry, are probably referable to the Pelorosaurus. As to the magni- 

 tude of the animal to which the humerus belonged, Dr. Mantell, while 

 disclaiming the idea of arriving at any conclusions from a single bone, 

 states, that in a Gavial eighteen feet long the humerus is one foot in 

 length ; i. e. one eighteenth part of the length of the animal, from 

 the end of the muzzle to the tip of the tail. According to these ad- 

 measurements, the Pelorosaurus would be eighty-one feet long, and its 

 body twenty feet in circumference. Even if we should assume the 



