262 Mr W. Macgillivray on the Covering of Birds. 



assumed that the accessory plumule is a provision of nature for 

 defending from the cold a bird so peculiarly exposed to it as they 

 imagine the ptarmigan to be. How these theorists may dispose of 

 the reasonings which they have founded upon such data, when 

 they examine the summer plumage of the ptarmigan, and find the 

 accessory feather equally developed in it, and comparing the red 

 grous with the ptarmigan, discover that it, too, is amply pro- 

 vided vdth a downy envelope of the same nature, I know not. 

 Moreover, if the bushy and downy accessory feather be a pro- 

 vision of nature for the defence of the birds of cold regions, why 

 should the argus, the Macartney cock, the jungle fowl, the Java 

 partridge, which inhabit the warmest regions of the globe, be 

 furnished with them, and that, too, in so high a degree ? The 

 subject of the accessory plumule might, as will be perceived, be 

 treated much more fully ; but my object not being to make it 

 occupy a more prominent place than other considerations, I must 

 relinquish it for the present, with the concluding remark, that, 

 in birds possessed of that sort of feather, the quills and large 

 tail-feathers, as well as the first row of superior and inferior 

 quill coverts, are in most cases perfectly simple, although there 

 are some birds, especially among the gallinaceae, and, in particu, 

 lar, the Lagopede grouse, which, in those feathers, have a very 

 distinct rudimentary accessory feather, existing in the form of a 

 short tapering lamina, fringed along its free edges with small 

 simple bards. 



Explanation of Plate III. 

 Fig. 1. Anterior dorsal feather of the cassowary, 

 2. Anterior dorsal feather of the emeu, 



These two figures shew the accessory feather in its high* 

 est developement, 



3. Inferior lateral cervical feather of Ardea cinerea, 



4. Dorsal feather of Tetrao saliceti. 



5. Dorsal feather of Polyplectron chinquis. 



6. Pectoral feather of Falco buteo. 



7. Part of a primary quill of the flamingo, shewing the union 



of the webs, 



8. Part of a primary quill of Tetrao saliceti, shewing the acces- 



sory feather existing in the state of a small pointed lami- 

 na, fringed with simple barbs. 



