ROOM III. THE MOSASAURUS OF MAESTRICHT. 193 



and fragile, as to render it extremely improbable that they 

 could have sustained such an instrument of flight as the 

 powerful wing of the Albatross ; their tenuity is indeed such 

 as to suggest their adaptation to support an expanded mem- 

 brane rather than pinions. 1 



I have recently collected from the Wealden strata of Tilgate 

 Forest some fragments of very .large cylindrical bones, the 

 walls of which are extremely thin, and unquestionably belong 

 to Pterodactyles. 



In concluding these notes on the flying Reptiles, I may 

 add that Mr. Bowerbank has procured from the Kentish 

 chalk, portions of jaws with teeth, more colossal than any 

 previously known : some portions of the upper maxilla prove 

 the total length of the head to have been upwards of sixteen 

 inches ; and the bones of the anterior extremity indicate a 

 width of from sixteen to eighteen feet, from the extremity of 

 one wing to the other ! 



The Mosasaurus, or Fossil Reptile of Maestricht. Wall- 

 case B. Maestricht, a large city in the interior of the Nether- 

 lands, situated in the valley of the Meuse, stands on a series 

 of calcareous arenaceous deposits belonging to the Upper 

 Chalk, and which gradually pass below into the pure white 

 chalk with bands of siliceous nodules. Extensive quarries 

 have for many centuries been worked in the sandstone, espe- 

 cially in the eminence called St. Peter's Mountain, which is 

 a cape or headland between the Meuse and the Jaar, formed 

 by the termination of a range of hills that bounds the western 

 extremity of the river valley. The mountain commences at 

 the distance of a mile south of the city, and extends in a 

 direction towards Liege for about three leagues ; it presents 

 an almost perpendicular escarpment towards the Meuse. 



The calcareous freestone, which is extensively quarried, is 

 soft and easily cut when first removed, but dries and hardens 

 by exposure to the air ; the total thickness of the strata is 

 above five hundred feet. 



1 A new part of the" Palseontographical Monographs" has just appeared ; 

 in which, commenting on this idea, Professor Owen states that the 

 wings of the Pterodactyles were composed of leather ! Start not, gentle 

 reader ! here are the very words. " It was reserved for the Author of 

 the 'Wonders of Geology* to prefer the leathern wings of the Bat and 

 the Pterodactyle as the lighter form." Prof. Owen, "Pal. Mon" 1851. 

 p. 83. 



