1896.] on the myologl of eodehts. 159 



Conclusion-. 



I do not feel justified in attempting to draw any general con- 

 clusions as to the relations of the various divergences from the 

 common type that I have described ; but I think that I have 

 brought together enough matter to show that when a much larger 

 number of facts has been collected, tiie method of investigation I 

 have been following may furnish another clue to that riddle of 

 zoology, the classification of birds. But in addition to this systematic 

 interest, the comparative anatomy of a group of creatures so large in 

 numbers and so alike in anatomical structure ofiers a field for the 

 investigation of the innumerable divergences and convergences 

 that have taken place in the evolution of the group. I cannot see 

 that interpretations of isolated characters have any value. When 

 we know the comparative anatomy of the greater number of 

 characters that make up an animal, and not only those that seem 

 to distinguish it as a species, the time may come for interpre- 

 tation. But to those who care for discussions concerning isolated 

 ciiaracters, I may suggest the problem : in these loopings of the 

 gut in birds, there is an almost kaleidoscopic variety, and appa- 

 rently these varieties are of systematic value ; v hat are their 

 utilities ? 



4. Myology of Rodents. — Part II. An Account of the 

 Myology of tlie Myomorpha, together with a Com- 

 parison of the Muscles of the various Suborders of 

 Rodents. By F. G. Parsons, F.R.C.S., F.Z.S., F.L.S., 

 Lecturer on Comparative Anatomy at St. Thomas's 

 Hospital. 



[Eeceiied December 14, 1895.] 



The present paper is intended to be a second instalment to the 

 one " On the Myology of the Sciuromorphine and Hystricomor- 

 phine Hodeiits," which I had the honour of reading before this 

 Society in 1894 (see P. Z. S. 1894, p. 2.51). I am again indebted 

 to the kindness of the Society's Prosector, Mr. F. E. Beddard, for 

 a large proportion of my material ; indeed, it was his suggestion 

 that a detailed examination of the muscles of Rodents would be 

 of practical value in the Dissecting-Eoom at the Gardens that 

 determined me to undertake the work in the first instance. 



The first part of this paper contains an account of the muscles 

 of thirteen Myomorphine Rodents, and as a statement of actual 

 facts will, I hope, prove of some value. 



The second part is devoted to a series of summaries and 

 generalizations founded upon the facts with which these and 

 previous dissections have furnished me. This part I regard as of 

 less value than the first, because future dissections may make 

 many alterations necessary. It seems well, however, to take 

 stock of the mass of material from time to time as it accumulates. 



