156 Royal Society. 



of the present phenomena ; and on this subject some extensive re- 

 searches have been pursued by Mr. Stokes of Pembroke College, 

 Cambridge, which will soon appear. 



"On the Meteorology of the Lake District of Cumberland and 

 Westmoreland." By John Fletcher Miller, Esq. Communicated by 

 Lieut.-Col. Sabine, R.A., For. Sec. R.S. 



The author has devoted nearly four years to the investigation of 

 the quantities of rain falling in the lake districts of Cumberland and 

 Westmoreland ; and he commenced, two years ago, a set of experi- 

 ments specially directed to ascertain the amount of rain deposited at 

 great elevations above the sea, such as the summits of our highest 

 English mountains. As the investigation proceeded, some remarka- 

 ble results were obtained, which coming to the knowledge of the 

 Royal Society early in last year (1847), the Council contributed a 

 sum of money from the Donation Fund towards the current expenses 

 attending this inquiry, of which the results are given in the present 

 communication, comprising extensive tables of observations relative 

 to the quantity of rain in different situations within the above period 

 of time. 



May 25. — " On the structure of the Jaws and Teeth of the 

 Iguanodon." By Gideon Algernon Mantell, Esq., LL.D., F.R.S., 

 Vice-President of the Geological Society, &c. 



The recent discovery of the right dentary bone of the lower jaw 

 of an adult Iguanodon with teeth, having enabled the author, with 

 the aid afforded by other specimens, to determine the structure of the 

 maxillary organs of that gigantic herbivorous reptile, the result of 

 his investigations are embodied in the present communication. 



The first memoir of the author on the teeth of the Iguanodon was 

 published in the Philosophical Transactions for 1825 ; but owing 

 to the fragmentary and water- worn condition in which the fossil re- 

 mains of terrestrial vertebrated animals occur in fluviatile deposits, 

 in consequence of these strata consisting of materials transported from 

 far-distant lands, nearly a quarter of a century elapsed before any 

 portion of the jaw with teeth was discovered. 



The most important of the fossils described in this memoir con- 

 sists of the anterior part of the right side of the lower jaw, which was 

 discovered a few weeks since, in a quarry in Tilgate Forest, by Capt. 

 Lambart Brickenden, F.G.S., who with great liberality placed it at 

 the disposal of the author as the original investigator of the fossils 

 of the Wealden. 



This dentary bone, which is eighteen inches long, is perfect in the 

 anterior part, but is broken at the hinder extremity, and retains five 

 or six inches of the coronoid bone : the length of the jaw to which it 

 belonged is estimated at four feet. It contains two successional teeth 

 in place, the fang of a third, and the alveoli or sockets for eighteen 

 or nineteen mature molars ; the entire number of teeth on each side 

 the lower jaw was about twenty. 



The mature teeth, which, when abraded by use in mastication, 

 resemble the worn molars of herbivorous mammalia, appear to have 



