RUBY-THROATED HUMMING BIRD. 



545 



•hollow Detween the eyes, which are very large, and the bill is dispropor- 

 tionately elongated. The pectoral muscles are of extreme size, ex- 

 ceeding by much the entire bulk of the rest of the body with the neck 

 and head, the height of the crest of the sternum being 4 twelfths, or 

 nearly half the length of the body. The body of the sternum is re- 

 markably flat, and so thin as to be almost perfectly transparent ; it is 

 narrow anteriorly, where it is 2j twelfths in breadth, but gradually 

 enlarges to 4 twelfths ; the posterior edge forms a semicircle, arjd is 

 destitute of notch. The pubic bones almost meet in front, where 

 they are cartilaginous. The heart is extraordinarily large, occupying 

 half the length of the cavity of the body, of an elongated conical form, 

 31 twelfths long, and 2 twelfths in breadth at the base. The right 

 lobe of the liver is much larger than the left, the former being 5 

 twelfths in length, the latter 4 twelfths. 



The whole length of the head is 1^ inch, of which the bill is 10 

 twelfths. The upper mandible is slightly concave beneath in its whole 

 length, the lower a little more deeply concave, the edges of both thin, 

 those of the lower erect and over- 

 lapped by the upper. The nostrils 

 are covered by a very large pro- 

 jecting membranous flap feathered 

 above. The tongue is, to a certain 

 extent, constructed precisely in the 

 same manner as that of the Wood- 

 peckers. The basi-hyal bone is 1^ 

 twelfth long, the apo-hyal bones 2 

 twelfths, the apo-hyal and cerato- 

 hyal together 1 inch 2 twelfths, the 

 glosso-hyal or terminal bones 4^ 

 twelfths. There is no uro-hyal bone, any more than in the Woodpeckers, 

 and the glosso-hyal is double at the end. The horns of the hyoid bone 

 are thus greatly elongated, recurving over the occiput, near the top of 

 which they meet, and thence proceed directly forward, in mutual proxi- 

 mity, lodged in a deep and broad groove, along the middle of the forehead, 

 until near the anterior part of the eye, where they terminate, Fig. 3 

 The crura of the lower mandible. Fig. 4, do not meet until very near the 

 tip, and from the inner and lower surface of each near the junction or an- 

 gle, there proceeds backward a slender muscle, which is attached to the 



VOL. V. 



M m 



