232 



ANATOMY OF VERTEBRATES. 



110 



The epiderm is in some places continued as a simple layer over 

 the corium, follo\^dng its wrinkles and folds, as around the naked 

 necks of some Vultures. It is moulded upon the bony mandibles 

 to form the beak, and in some Birds adheres to osseous pro- 

 tuberances on the cranium, where it forms a species of horn ; and 

 it is remarkable that these instances occur chiefly in those orders of 

 Birds, the Cursores and Rasores, which are most analogous to the 

 Ruminantia among quadrupeds : the Cassowary and Helmeted 

 Curassow are examples. The Hornbills are, however, instances 

 in the Yolitorial, and the Kamichi in the Grallatorial Order. The 

 cuticle is sometimes developed into spines or spurs, as upon the 

 wing of the Snake Vulture, Cassowary, Palamedea ; and upon the 



leg of many Gallinaceous Birds. 

 The claws which sheath the 

 unguial phalanges of the feet 

 assume various forms adapted to 

 the habits and manner of life of 

 the different orders. A remark- 

 able artificial form is given to the 

 claw of the middle toe in certain 

 Birds ; the inner edge being pro- 

 duced and divided into small 

 parallel processes like the close- 

 set teeth of a comb, fig. 110. 

 These teeth are not reflected or 

 recurved, as they might be ex- 

 pected to be, if they had been intended to serve as holders of a 

 slippery prey, but are either placed at right angles to the claw or 

 are inclined towards its point. The Common Barn-Owl (Strix 

 flammea), the Night-jar genus ( Caprimulgus)^ the Heron and 

 Bittern kind (^ArdeidcB, ^igO' ^Aoi'd examples of this structure ; 

 and as each species of bird appears to be infested by its peculiar 

 louse (Nirmus), the solution of the final intention of so singular a 

 contrivance, which is limited to so few species, and these of such 

 different habits, may yet be afforded by the entomologist. 



With respect to the scales which defend the naked parts of the 

 legs of birds, they do not differ from those of Reptiles. Their 

 form and disposition, as has been already observed, have afforded 

 distinctive characters to the zoologist. In most of the Raptores, 

 the Psittacidce, the Rasores, the Grallatores, and the Natatores, the 

 scales are polygonal, small, and disposed in a reticulate form ; the 

 birds so characterised formed the Retipedes of Scopoli. In the 

 rest of the class the tarsi are covered anteriorly with unequal 



Foot of Night-jar. 



