DEVELOPMENT. 213 
the Rhinoceros, the horns are odd, 7. ¢., single, or two 
placed one behind the other. Creatures with feathers al- 
ways have beaks. Pigeons with short beaks have small 
Fie. 175. 
Fia. 177. Fig. 178. 
HOMOLOGIES OF LIMBS, 
Fig. 175.—Arm and Leg of Man, as they are when he gets down on all fours. Fie. 
176.—Fore and Hind Legs of Tapir. Fia. 177.—Fore Leg of Seal and Hind Leg 
of Alligator. Fie. 178.—Wing of the Bat. §S, scapula; I, ilium, or shin-bone of 
pelvis; H, humerus; F, femur; O, olecranon, or tip of the elbow; P, patella; 
U, ulna; T, tibia; R, radius; Fi, fibula; Po, pollex, or thumb; Ha, hallex, or 
great toe. Compare the fore and hind limbs of the same animal, and the fore 
or hind limbs of different animals. Note the directions of the homologous seg- 
ments, 
