344 ON THE GENUS PTILOPUS. 



What is the use of this sweUing ? — a most difficult question, and one 

 which may be asked concerning other species as well as the one before us, 

 notably Pauxis galeata &c. among the Curassows, the Bucerotidse also. 



On relaxing the skin of my specimen, and opening the mandibles, 

 it presented a very different appearance from what it did in its contracted 

 condition. It became manifest that the protuberance is essentially a feature 

 belonging to the beak, beyond the base of which it does not extend ; neither 

 has it any connexion with or relation to the brain. I was tempted to make a 

 section straight through the middle ; but it would spoil the bird and 

 probably tell nothing. 



The following extracts from a foreign author are added, without giving 

 any opinion as to his views on the subject under discussion : — 



William Marshall : Ueber die knochernen Schadelhocker der Vogel. 

 [On the Bony Protuberances of the Skull of Birds.] Haarlem and 

 Leipzig, 1872. 8vo, 47 pp., 2 pis. 



Page 13 :— 



" Among the Pigeons, some of the subfamily of the Carpophagin^ are 

 remarkable in respect to the protuberances at the base of the upper 

 mandible ; but these are merely formed by the cere. In this respect they 

 ought not to be considered here ; but I am of opinion that the mode of the 

 occurrence of the phenomenon in this family also throws light on the origin 

 of the bony protuberances in other birds. In Carpophaga QGloUcerd) pacifica, 

 Reich., the swelling of the cere is not a large one, and it is of a black colour ; 

 in C. ruhricera, Gray, it is more conspicuous, and of a fine red colour. But 

 the most interesting is C. roseinucha, Schlegel. There are two races of this 

 bird, each having a special geographical range. The one occurs in New 

 Guinea ; and the adult has in both sexes a protuberance, which is often very 

 conspicuous; this race, therefore, belongs to the subgenus GloUcera, in 



