438 



Dr. W. J. Russell and S. West. [May 27, 



less, I am able, after many years of labour, to give an account of 

 the adult skull in seventy kinds, and of the larval— -in one or several 

 stages — in a good number of the species. 



The illustrations are, for the most part, put in a similar manner in 

 all the plates ; and, as to size, I have not made the skulls of the dwarf 

 kinds much less than those of the large types. 



I am satisfied that these figures and descriptions will be found 

 useful, not merely for comparison of the types of larval and adult 

 Batrachian skulls one with another, but I believe that they will throw 

 light upon, and in turn be illuminated by, all that we can learn of 

 the structure and development of the skull in the other types of 

 Vertebrata. 



With regard to the geographical distribution of the Batrachia, there 

 are many things of importance which I have rather hinted at than 

 expressed in this paper. 



There is a sort of fades or character about the allied types of any 

 great geographical region which makes me satisfied that certain 

 external characters repeat themselves again and again in different 

 parts of the world. 



Thus, the types of frogs that have dilated toes are evidently more 

 nearly related to those with pointed toes of the same region than 

 they are even to the broad-toed types of some distant region. 



I should be inclined to derive the narrow- backed tree frogs of 

 Australia from the sharp-toed frogs of the same region ; the same with 

 those of India, and the same with those of the nearctic and neo- 

 tropical territories. 



The true frogs (" Ranida3") of India have many things in common, 

 as also have the true frogs of North America ; the same may be said of 

 the sub-typical frogs, or " Cystignathidas." 



On the whole, the European and Indian territories yield the highest 

 kinds ; Australia and South America the lowest and most generalized. 



IY. " On the Relation of the Urea to the Total Nitrogen of the 

 Urine in Disease. No. I." By W. J. Russell, Ph.D., 

 F.R.S., and Samuel West, M.B. Oxon. Received May 6, 

 1880. 



In the valuable series of papers upon the excretion of urea, com- 

 municated by Professor Parkes to the Royal Society, he showed that 

 in health 90 per cent, of the nitrogen in the urine, was eliminated in 

 .the form of urea. It seemed to us of considerable interest and im- 

 portance to ascertain whether in disease this statement still held good, 

 or whether, as indeed seemed probable, under altered conditions, 



