THE LIMBS IN GENERAL. Ill 



meditations. In such a matter, it must not be forgotten that the limbs are 

 constructed with a view to their physiological functions, and that the 

 differences remarked in examining them in several species are dictated by 

 the kind of life the animals are intended to lead. 



Vicq-d' Azyr and Cuvier recommend that the anterior and posterior limbs 

 of opposite sides should be compared. Martins and Gegenbaur, allowing a 

 torsion of the humerus of 180, advise that the two members of the same 

 side should be collated, care being taken to make allowance for the 

 untwisting of the 180 contortion at the lower end of the humerus. 

 Lastly, Flourens and Lavocat contrast the two members of the same pair 

 with each other, after placing the hand in a position of natural pronation by 

 rotation of the radius on the ulna, and without turning either limb or ray, or 

 even a portion of a ray, no matter what kind of animal may be under 

 examination. We will adopt the latter proceeding, as it is the simplest and 

 most natural. 



Parallel between the coxa and scapula. The analogies existing between 

 these two bones are but little striking at first sight ; nevertheless, with atten- 

 tion there is no difficulty in finding in the coxa the three pieces that enter 

 into the composition of the shoulder. 



The ilium represents the scapula. The external iliac fossa reminds one 

 of the supra- and subspinous fossae. Occasionally, there is met with in the 

 Horse a rudiment of the crest dividing the iliac fossa into two parts, and, in 

 some animals the Pig, Sheep, and Goat this crest, which is the trace 

 of the scapular spine, becomes constant and very evident. 



With regard to the cotyloid cavity, it repeats in the posterior limb the 

 glenoid cavity of the scapula. There remains to determine in the latter 

 bone the portions analogous to the ischium and pubis. If we rely upon the 

 evidence afforded by the muscular insertions, we come to the conclusion that 

 the ischium corresponds to the coracoid process, and the pubis to the clavicle 

 of animals which are provided with one. It will also be remarked that the 

 coxa is directed backwards, while the scapula inclines obliquely forwards ; 

 this opposition in the direction of the bones in no way alters their analogies ; 

 the functions of the members to which they correspond require this inverse 

 position. 



Parallel between the femur and Jiumerus. The resemblance between 

 these two bones is remarkable. Thus there is found in the first : 1, An 

 articular head, better detached than that of the humerus, but shaped in the 

 same manner ; 2, A trochanter analogous to the great tuberosity, and also 

 like it decomposable into three distinct parts summit, crest, and convexity ; 

 3, A lesser trochanter, representing the smaller tuberosity ; 4, An eminence 

 for the insertion of the superficial gluteus muscle, which takes the place of 

 the deltoid imprint ; 5, An inferior articular pulley continued between the 

 two condyles by a non-articular groove ; this trochlea certainly corresponds 

 to the median groove of the inferior humeral face. 



There are, no doubt, differences between the two bones, but they have 

 no bearing upon the result just indicated. Thus the linea aspera of the 

 femur is situated behind ; that of the humerus in front. In the femur the 

 two condyles of the inferior extremity are placed behind the trochlea ; the 

 contrary holds in the humerus. These modifications are necessary in order 

 to give the movements of the limbs a convenient direction. The leg is 

 flexed backward on the thigh, while the fore-arm is flexed in front on the 

 humerus. 



Parallel between the bones of tlie leg and those of the fore-arm. It is 



