404 BIRDS. 



out on each fide in parallel rows clofe to each other j and thefe are double in water 

 fowls which have pinnated feet. 



The feathers of birds are gaily ornamented with colours, which are varied by diffe- 

 rence of age, fex, feafon of the year, and climate ; but on the quill-feathers of the 

 wings, remiges, and of the tail, reclrices, thefe colours are more conftant, and deferve 

 an attentive confideration from the ornithologift, as being frequently the only diftinc- 

 tive marks of fpecies *. A naked ftripe of the Ikin runs down on each fide of the 

 neck, from the head, pointing towards the fpace, interfcapulium, between the fhoulders 

 of the wings ; and another fimilarly naked fpace on each fide from what are called the 

 Armpits, axillae, under the wings, along the fides of the breaft, backwards almoft to the 

 groins and thighs. 



All birds are oviparous, or produce eggs, which contain the rudiments of their 

 young; the number of thefe is various in the different kinds, but they are always co- 

 vered with a calcareous cruft, or (hell, and, after exclufion from the mother, they are, 

 almoft univerfally, depofited in artificially conftrucled nefts, in which, by what is term- 

 ed incubation, the parents fit on them, to keep them warm, till they are hatched. 



The windpipe, trachea, is compofed of cartilaginous rings, and is furnifhed with a 

 great number of mufcles ; and in many birds the branches, or branchiae, of the wind- 

 pipe are Iikewife furrounded with cartilaginous rings. 



Through the whole body a number of air cells are interfperfed, even in the bones ; 

 thefe cells are connected with the lungs, and may be filled or emptied at pleafure; they 

 are of fingular ufe for flight, by rendering their bodies lighter, in proportion to their 

 bulk, and they afiift in prolonging their fongs : Thefe cells are fituated in the cellular 

 membrane of the belly, under the wings, and in other places ; and, except in the order 

 of Anferes, and the genera of Coots and Snipes, they are chiefly diftributed in the ca- 

 vities of the bones, which are void of marrow ; fuch as the bones of the thighs and 

 wings, the breaft-bone, ribs, rump-bones, fhoulder blades, collar-bones, back-bone, and 

 even fometimes in the bones of the fkull and the lower jaw. 



A bird, for the purpofes of defcription, is diftinguifhed into the Head, the Body, and 

 the Limbs. The covering of the top of the head is called the pileus, or Cap, which is 

 diftinguifhed into the Front, from, the Crown, vertex, and the Hind-head, occiput: 



That 



„-* Act. Stockholm. 1740, p. 370. t. i. f.'io. 11. 



