220 



Div. 1. VERTEBRATE ANIMALS.— AVES. 



Class 2. 



the water to a certain depth without immersing tiie feathers, aiul to wade therein and seize 

 fish by means of the neck and beak, the length of which is generally proportioned to that of 

 the legs. The stronger among them feed on fish and reptiles, and the weaker on worms and 

 insects. A very few content themselves in part with grain or herbage, and these alone inhabit 

 at a distance from any water. Their external toe is most commonly united at base to the 

 middle one, by means of a short membrane; in some there are two membranes, while others 

 want them entirely, having the toes quite separated ; it also sometimes happens, though 

 rarely, that they are palmated to the end : the thumb is altogether wanting in several genera; 

 and all these circumstances exert an influence on their mode of life, which is more or less 

 aquatic. Nearly the whole of these birds, if we except the Ostriches and Cassowaries, have long 

 wings and fly well. They stretch out their legs backward during flight, contrary to what is ob- 

 served of others [or at least those of the foregoing orders], which double them under the belly. 



In this Older we establish five j)rincij)al families, together with some isolated genera. 



The first family of Stilt Birds, that of 



The Brevipennes, 

 Although generally similar, in other respects, to the rest, differs widely from them in the 

 shortness of the wings, which are inadequate to perform the function of flight. The beak and 

 regiroen give them numerous affinities with the GnUinacecB. 



It appears as if all the muscular power which is at the disposal of nature, would be insuffi- 

 cient to move such immense wings as would be required to sui)port their massive bodies in 



the air: their sternum (fig. 111.) is a 

 sim])le buckler, and without the ridge 

 which exists in all other Birds. The 

 pectoral muscles are reduced to ex- 

 treme tenuity ; but the posterior ex- 

 tremities regain what the wings have 

 lost. The muscles of their thighs, 

 and of the legs especially, are of an 

 enormous thickness. 



[Most, if not all, of these birds, are 



remarkable for their singular mode of 



incubation. In the Ostrich, Emeu, 



and Nandou, it appears that several 



females lay in the same nest, the eggs 



being chiefly sat upon by the male, 



who feigns lameness when disturbed : 



FiK.n2-st«num of Ostrich. ^^ artificc practised by the generality 



of ground- birds. It may therefore be presumed that they are polygamous, the attendant 



femal -• of each male depositing their eggs together, commonly to the number of thirty, or 



C' more.] 



I hey all want the back-toe. In the Ostrich, the number of phalanges to the two front-toes 

 are four and five ; in the Cassowary, [F-meu,] and Nandou, the ])halanges of the three front- 

 toes number three, four, and five, resj)ectively. We recognize two genera. 



The Ostriches {Struthio, Lin.), — 

 Have lax and flexible feathers on the wings, which latter are sufficiently long to accelerate tlieir speed. 

 Every one is acquainted with the elegance of these slender-stemmed feathers, the barbs of which, 

 though furiiished with secondary barbules, do not hitch in each other, as is the case with feathers 

 generally. Tlie beak is horizontally depressed, of mean lengtli, and blunt at the tip; the tongue short, 

 and rounded like a crescent ; and the eye large, with its lids garnished with lashes. Their legs and 

 tarsi are very long. They have an enormous crop, and considerable proventiiculus between the crop 



