766 EXPLANATION OF PLATES. 



nal finger (pp. 329 333). The bones of the limbs of the right 

 side are omitted in this figure. 



Fig. 2. Sternum and clavicles of the same bird seen from before ; c, c, 



0, o, L, as in the preceding figure. 



Fig. 3. Skull of the ostrich, Struthio camelus, p. 417, from the side and 

 reduced; a, frontal bone; b } nasal bones; c, superior maxillary 

 bone; d, malar bone (d', quadrato-jugale, squamosal Ow.); e, 

 quadrate bone (tympanic Ow.); e, temporal bone (mastoi'd 

 Ow.); f, parietal; g, g' } occipital bone; g' t unpaired upper 

 piece (pars occipitalis), g, lateral occipital (ex-occipital Ow.); 



1, intermaxillary bone; k t lower jaw composed of different 

 bones (u, v, x, y, compare the skull of crocodile, PL iv) ; I, sphe- 

 noid bone; t foramen opticum; m, anterior ala (orbit o-sphe- 

 noi'd Ow.). 



Fig. 4. Connexion of the quadrate bone with the os omdideum on the 

 inferior surface of the skull, in Crax globicera. Compare 

 pp. 333, 334; I, sphenoid bone; o, os omcftdeum; p, palate- 

 bone; q, q, quadrate bone. 



Fig. 5. A hen's egg that has been brooded about 24 hours, seen from 

 above, but so that the section only of the shell and its mem- 

 brane is represented ; from Y. BAER Ueber Entwickelungsgesch. 

 der Thiere, i. Taf. in. fig. 3; a, the shell; b, the shell-mem- 

 brane ; c, boundary between the external and middle albumen ; 

 c, ligamentum albuminis of TREDERN ; d, boundary between the 

 middle and internal albumen; e, e, chalazce; g, boundary of 

 the germ-membrane (blastodermd) ; g, h, the vitelline circle; 

 h, boundary of the foetal area; h, i, the vascular area; i, the 

 space in which the embryo lies; this last is seen as a transverse 

 streak in the middle of the space, pp. 351, 352. 



Fig. 6. Eye of the swan, horizontal section, after D. W. SOEMMERRING, 

 a, optic nerve; b, sclerotic; c, cornea; d, crystalline lens; e, 

 pecten, pp. 365 367. 



Fig. 7. Tongue of RJiamphastos (lingua pennacea) with the tongue- 

 bone reduced, p. 446. 



Fig. 8. Tongue-bone of Pavo cristatus, reduced, compare p. 364. 



