506 THE GANNET 



sometimes done, the working of the joint can be plainly seen. 

 Across the lower jaw there is another hinge, probably to 

 increase the width of the gape when feeding the young. 

 The tip of the beak is slightly curved, and a deep groove, 

 generally termed the nasal-groove, runs along the sheath 

 of the upper mandible, and is continued to the end. 

 The roof of the mouth is supplied with raised edges, 

 another provision for holding a fish when caught. 



The Olfactory Apparatus. — The Gannet has no external 

 nostrils, although the position where they might be expected 

 is indicated; the exact spot lies at the posterior end of a 

 deeply indented furrow, on the sides of the upper jaw, or 

 mandible, which in a nestling Gannet is very pronounced. 

 But although there are no nostrils, the olfactory chamber 

 is nevertheless fairly well developed,'^ but it is improbable 

 that the power of smell is much developed (c/. p. 384). 

 Certainly it does not equal that of the Petrels. 



The Sternum. — The sternum or breast-bone, which sup- 

 ports the coracoid bones, is a very important part of a 



* See Dr. Hans Gadow in Bronn's " Thier-reichs " (VI., p. 452). In 

 the Cormorant, Mr. F. A. Lvicas finds the nares open for four or five weeks 

 after birth, but is of opinion that they close when the young ones take to 

 the water (c/. "The Auk," 1897, pp. 87, 205). Their position in the young 

 of this species has been shown by Mr. W. P. Pycraft, in an article in the 

 Linnean Society's "Journal " ("Zool.," XXVII., p. 207), from which the 

 annexed drawing is borrowed with permission. 



