BIRDS. 363 



quite naked, however they be protected by the vanes of the 

 neighbouring quill-feathers. The various disposition of these 

 feathered regions has been carefully investigated by NITZSCH in 

 different genera of birds, and has been employed as an aid in 

 classification 1 . The quill-feathers of the wings and of the tail 

 bear different names. The large quill-feathers, which are inserted 

 in a row on the outside along the posterior margin of the hand and 

 the fore-arm, are named flag-feathers (remiges}. Ten or nine (some- 

 times eleven) of these are inserted on the hand from the point of 

 the wing as far as the joint (remiges primo-res s. remiges primi or- 

 din-is); to them succeed the so-named secondary flag-feathers (remiges 

 secundi ordinis], which are subject to a much greater variety of 

 number and are attached to the ulna. The thumb-wing (alula, 

 ala spuria] is a bundle of small stiff feathers inserted externally on 

 the thumb. Sometimes there is a carpal tubercle above the thumb, 

 covered with a conical horny investment. The wings are in that 

 case said to be spurred (alee calcaratce), as in Parr a jacana L., 

 Palamedea, &c. The great quill- feathers of the tail are named 

 rudder-feathers (rectrices) 2 . The large quill-feathers of the wings 

 and the tail are covered by smaller feathers (coverts, tectrices ; the 

 tail-coverts are named calypteria). 



Cutaneous glands or sebaceous and sweat glands, which in 

 mammals are commonly present in great numbers, and are diffused 

 over most parts of the body, are wanting in birds, with the excep- 

 tion of a gland situated under the skin, on the tail-bone, which, 

 however, in some is absent. It consists of two lobes, formed of 

 blind, parallel tubes, and secretes a white or yellow oily substance, 

 which the birds press from the excretory ducts with their bill and 

 with which they smear their feathers. These glands are more 

 developed in some water-birds (especially in Sula, Sterna, Procel- 

 laria] than in the rest 3 . 



1 C. L. NITZSCH System der Pterylograpkie, Mit x Kupfertafeln, Halle, 1840, 4to. 

 In the supplements also by the Editor, Prof. BURMEISTER, contributions to the history 

 of the development of feathers are to be found, which may be compared with what has 

 been stated above. 



3 In the description of birds these feathers are counted from without inwards so 

 that each of the outermost feathers is named the first, those that succeed to them the 

 second, &c. up to the middlemost. 



3 Compare SCHNEIDER Abhandlungen zur Aufklarung der Zoologie u. Handlungs- 

 gescJiichte, 1784, s. 158, 159, 333, TIEDEMANN Zoologie, n. s. 135137, NITZSCH 

 Pterylographie, s. 54 59. 



