Feather stonhaugh's Geological Report. 85 



of which have jaws near nine feet in length, with strong pad- 

 dles to enahle them to go through the waters. This animal, 

 to the vertebra of a fish unites the head of a lizard and the 

 powerful teeth of a crocodile. The plesiosaurus is another 

 monster with the head of a lizard and a singularly long neck, 

 which at one time it was supposed to carry after the manner 

 of a swan in the shallow waters near the shore, but which it 

 perhaps projected in the water rather after the manner of a 

 serpent. This animal also has paddles. But the most curious, 

 because we have nothing which resembles them nearer than 

 the vampire bat, is the pterodactylus, a saurian animal, with 

 extended membranaceous wings ; this is the first decided case of 

 an aerial animal, and, like the rest, was undoubtedly of the vora- 

 cious kind. The smaller skeletons of these animals are usually 

 found in the lias, much flattened from the great pressure upon 

 them, but often entire, with even the faeces in the visceral 

 region, as if they had been surprised by a violent and sudden 

 death from some extraordinary convulsion which had happened 

 and in the consequent results of which their remains had been 

 immediately enveloped and preserved. The faeces, or copro- 

 lites, as they are now termed, have been analyzed, and their 

 true character ascertained. In most of them, the scales of fish 

 are found, and in some, the undigested remains of the young 

 of their own kind. Notwithstanding the immense period of 

 time they have been entombed, some of the teeth and bones 

 of these animals have yielded about 50 per cent, of phosphate 

 of lime. A great number of species of these saurians occur, 

 besides other genera which are not mentioned here. The 

 saurian remains of the United States have been hitherto frag- 

 mentary, and belong to the subcretaceous beds. This group 

 is also further remarkable for having produced the first un- 

 questionable remains of terrestrial mammalia, in the didelphoid 

 quadruped, as it is usually termed, an extinct species of opos- 

 sum, first found in the slaty oolitic beds of Stonesfield, in Ox- 

 fordshire, lying beneath the cornbrash. Some doubt was for- 



