1867.] DR. J. MURIE ON CYGNUS BUCCINATOR. 11 



now in the College, The trachea in it, as Yarrell (loc. cit.) has de- 

 scribed and most beautifully figured in a profile section of C. buc- 

 cinator, comes down the neck, enters the keel, runs backwards to 

 near the posterior end of the sternum, loops round and returns, en- 

 tering the second highly raised hollow protuberance on the dorsum, 

 again dipping ere it makes its exit under the furcula. 



So far this all agrees with what Prof. Hiucks says of C. puss- 

 mori ; but this author lays stress on the shape and size of the bony 

 expansions lodging the bent trachea, and describes afresh the struc- 

 ture in what he believes to be the true C. buccinator. 



The College specimen has the posterior osseous expansion 3* I 

 inches long, and 1'2 broad at its greatest diameter. This expansion 

 is of an oval shape, rather truncated behind, and placed very much 

 to the left side of the median line, excentric in this particular. Its 

 right side is lowest ; at '6 inch from that edge, and almost at what 

 corresponds to the middle of this part of the sternum, is a slightly 

 depressed longitudinal furrow ; from this to the left mai'gin the bony 

 expansion rises more quickly, until attaining a maximum height of 

 Ytj of an inch above the horizontal sternal plate ; the left edge is 

 nearly perpendicular. 



Between the anterior end of the posterior and the posterior end of 

 the anterior osseous protuberance, the superficial protecting lamina 

 of bone is wanting, here exposing the trachea. 



The anterior, smaller but much more elevated hollow is some- 

 what heart-shaped, the indented broader end forwards ; but here a 

 a narrow isthmus of bone joins it to the anterior sternal arch. On 

 its left superficies it is somewhat low and flattened, where rests the 

 laterally compressed termination of the trachea, before giving off the 

 enlarged globiform bronchise. 



On the right moiety the bone rises | of an inch higher, and is as 

 it were compressed on either side, but has a high arched form when 

 viewed in profile. The dimensions of this bony protuberance are 

 1*.5 inch from before backwards, and fully 1 inch in its greatest 

 transverse diameter. It is raised a little more than an inch above 

 the highest level of the outer sternal plate of bone, to which the fore- 

 most ribs are attached. 



The two posterior sternal emarginations are finger-shaped, and 

 above an inch deep. The left one is overlapped and partially hidden 

 by the after tracheal protuberance (see fig. 1). The greatest length 

 of the entire sternum is 8| inches ; the extreme breadth, viz. poste- 

 riorly, equal to 4 inches. 



The side view agrees in the main with Yarrell's figure ; Hincks's 

 does not display the details of structure so accurately. 



Looked on from above or inside, as in the figure (fig. I), the 

 two costal edges have a long but shallow concave outline, so as to 

 produce a tendency to a sand-glass form. 



In the total length of the sternum and in the height and inclina- 

 tion to the right of the anterior protuberance it thus corresponds to 

 Hincks's description of his C. buccinator ; but the breadth agrees 

 with C. pussmori and with Yarrell's ('. buccinator. The tracheal 



