8 DR. J. MURIE ON CYGNTJS BUCCINATOR. [Jan. 10, 



leche) might be said to be the South-African prototype of the West- 

 African iEquitoou {Adenota kob), notwithstanding that tbese forms 

 are found within a short distance of a parallel northern latitude. In 

 the one case the animals inhabiting the southern equinox are darker 

 and larger than those of the northern 'equinox. Examples might be 

 given of other animals presenting analogous shades of diiference : for 

 instance, the Giraffes found north and south of the equatorial line have 

 by some naturalists even been considei'ed specifically distinct; and 

 other authors point out like shades of difference in the Elephant &c. 



How far such suggestions are surmise, and how much based on 

 wider generalizations, more extended facts would better determine ; 

 but such thoughts do arise on considering what has been.shown to 

 occur in the fauna of other extensive continents, e. g. in the insects 

 and birds of South America. 



2. On Cygmis buccinator, Ricliardson^ and Cygnus passmori, 

 Hincks. By James Murie^ M.D., F.G.S., Prosector to 

 the Society. 



The Rev. W. Hincks, F.L.S., Professor of Natural History in the 

 University of Toronto, Canada, communicated to the Linnean Society, 

 on the 21st January 1864*, a short but suggestive paper, wherein 

 he gave to a specimen of Trumpeter Swan the name of Cygnus pass- 

 tnori. In a letter dated 10th of x\pril, and subsequently read on the 

 5th of May of the same year, he, however, threw out hints of the 

 possibility of an error of judgment on his part, as further investi- 

 gation led him to believe that the difference in individual specimens 

 which he at first was inclined to regard as specific might really not 

 be such, but rather be attributable to gradation of form connected 

 with age. 



The facts brought forward by that gentleman, so far as I know, 

 have thus been left in uncertainty ; and hence arises the interrogation, 

 Are there characters sufficiently distinct and constant to warrant" a 

 separation of the Trumpeter Swan into two species ? or is the varia- 

 tion in individual form merely a modification or progression of 

 growth as suggested by Prof. Hincks? 



I will in the present paper endeavour to answer these questions, 

 at least as far as the evidence goes which the examination of three 

 specimens afiFoi'ds. 



These were added to the Zoological Society's Collection in the 

 Regent's Park on the 10th of May 1866, and assumed to be the true 

 Trumpeter Swan {Cygnus buccinator of Richardson). Two of the 

 birds died a short time after their arrival, and afforded me an oppor- 

 tunity of examining that part of the skeleton in which the chief 

 grounds of specific separation are found, viz. the sternum, which in 



* Published intlie 'Journalof the Proceedings of the Linnean Society,' vol. viii. 

 (1865), pp. 1-7. 



