Meeting held in the Library of the Philosophical Hall, November 3rd, 

 1890. J. Charters Birch, L.D.S., in the chair. 



THE STERNA AND SHOULDER GIRDLES OF BIRDS. 

 EDGAR R. WAITE, F.L.S. 



Sterna are of very great value to the naturalist, as they are largely 

 used for the purpose of classification. If we turn our attention toVe 

 classification of birds we are met at the very outset by the sternum. Birds 

 are divided into two great classes, the Ratita: and the Carinatce. The 

 Ii«tit<B include all the trLie nou-ilying birds, such as the Ostrich, Emu, and 

 Apterys, &c. The sternum of these birds is quite ilat, like a raft, from 

 the resemblance to which they take their name. The Carinatce, on the 

 other hand, possess a "carina" or keel to their sterna, and are capable of 

 flight. The sterna of all flying birds do not bear the same relative size. 

 Those birds which have a large keel are much better flyers than those 

 which have a much smaller one ; this was well seen on comparing the 

 keels of the Woodpecker and the Sand Grouse : that of the latter bfrd is 

 more than twice the relative size of the former, and the difl'ercnce in their 

 flight is correspondingly marked. The Woodpecker does little more than 

 fly from the top of one tree to the bottom of another, while the Sand 

 Grouse "goes like the wind." After giving a description of the various 

 bones comprising the sternal girdle and the muscles connected with them, 

 the peculiarities of variation in dififerent families of birds was next 

 pointed out and explained, among other things why tte Swifts should be 

 separated from the Swallows, and why the Strigklw should be removed 

 from the other Owls. In dealing with the fnrculum (or merrythought). 

 It was shown that its principal function appeared to be to keep the head 

 of the shoulder-bones apart during the down-stroke of the bird. In the 

 FaJconidee (Eagles, Hawks, &c.), this bone forms a perfect arcli, capable of 

 resisting great pressure ; while in some other birds it is long, thiu, and 

 weak, e.g., in the Grouse family, and in non-flying birds it is rudimentary 

 or entirely absent. Speaking of the coracoids, Mr. Waite showed that in 

 many birds these bones were incapable of more than a very slight move- 

 ment on the sternum; but in others, such as the Gannet-a powerful 

 divmg bird— it was shown that the movement is very great, and by this 

 means the shock of the bird entering the water is broken. The address 

 was illustrated by a large collection of sterna and by many diagrams. 



Meeting held in the Medical School, November 10th, 1890, Professor 

 de Burgh Birch, M.D., CM., F.E.S.E. (President), in the chair. 



DEMONSTRATION OE DIGESTION. 

 PROFESSOR BIRCH. 



It was shown at the outset that digestion was the conversion of 

 substances into such a condition that they can be absorbed into the body. 



