THE RUBY-THROATED HUMMING-BIRD. 



197 



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| inches, 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 7 



of both thin, those of the lower erect and 

 overlapped by the upper. The nostrils are 

 covered by a very large projecting mem- 

 branous 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 lj twelfths 

 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 proximity, 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 angle, there proceeds backward a slender 

 muscle, which is attached to the hyoid bone at the junction of 

 the apo-hyal and cerato-hyal, whence it proceeds all the way to 

 the tip of the latter, the muscle and bone being enclosed in a 

 very delicate sheath, which is attached to the subcutaneous 

 cellular tissue between the nostrils. The tongue, properly so 

 called, moves in a sheath, as in the Woodpeckers; its length is 

 10 twelfths. When it is protruded, the part beyond this at the 

 base appears fleshy, being covered with the membrane of the 

 mouth forming the sheath, but the rest of its extent is horny, 

 and presents the appearance of two cylinders united, with a deep 

 groove above and another beneath, for the length of 3 twelfths, 

 beyond which they become flattened, concave above, thin-edged 

 and lacerated externally, thick-edged internally, and, although lying parallel 

 and in contact, capable of being separated. This part, being moistened by 

 the fluid of the slender salivary glands, and capable of being alternately 

 exserted and retracted, thus forms an instrument for the prehension of small 



