398 MR. ST. G. MIVART ON THE ANATOMY OF ECHIDNA HYSTRIX. 
ment of the parts concerned. He calls attention to the embryonie condition of the 
limbs, before alluded to, adding (as reported) that “that embryonic condition continues 
throughout life in many Amphibia and Reptiles, and without much change in Galeo. 
pithecus among Mammals.” He then makes the comparisons before mentioned between 
the scapula and ilium, grounding his determinations on the conditions presented by 
the Ornithorhynchus. 
The Echidna, however, presents certain differences from the Ornithorhynchus, as may 
already have been gathered from the first part of this paper. In the Echidna, as in the 
Ornithorhynchus, the apparent anterior costa of the scapula is really the edge of its spine 
and acromion, the supraspinatus fossa is on the internal costal surface of the bone, and 
the infraspinatus fossa is immediately behind its actual anterior margin. But while in 
the Ornithorhynchus the subscapularis occupies that part of the internal or costal surface 
of the scapula which is not occupied by the supraspinatus, in the Echidna, on the other 
hand, the subscapularis occupies exclusively the external surface of the scapula. 
The true nature of these muscles is determined by their insertions—the supraspinatus 
being inserted, in common with the infraspinatus, into the greater or radial tuberosity; 
while the subscapularis is inserted into the lesser or ulnar ! one, somewhat above the in- 
sertion of the teres major. 
Such being the condition of the anterior limb, we find, when we turn to the pelvie 
region and thigh, a certain unmistakeable resemblance between the muscles inserted 
into the lesser tuberosity and those implanted into the greater trochanter, ?. e. between 
what I have called the gluteus minimus (but which may be the gluteus medius) and the 
subscapularis, and between what I have called the gluteus medius (but which may be? 
deeper portion of the gluteus maximus) and the teres major. 
Moreover, when we observe the peculiar position of the scapula in the Echidna, it 18, 
I think, almost impossible to avoid being struck with the correspondence in this ani 
of the outer (in it subscapular) surface of the scapula with the outer (gluteal) surface of 
the ilium, and being tempted once more to reconsider the serial homologies of the parts 
connected with the proximal ends of the humerus and femur respectively. 
Accepting, as satisfactorily demonstrated, the correspondence between the extensor 
surfaces of the fore and hind limbs, and recognizing that these extremities are p 
in an essentially similar position when the radius and pollex, the tibia and hallux a 
all turned forwards, while the palm and sole, with the flexor surfaces of the limbs, wid 
all directed inwards, we yet find certain discrepancies, one being that the articular hend 
of the humerus is turned backwards, while that of the femur looks, and is prolonged, , 
a forward direction. 
It is mainly, perhaps, this fact which has occasioned so many laboured, and more © 
less ingenious, endeavours at explanation, by suggestions that the right fore limb answer 
to the left hind limb and vice versá, or that a greater or less rotation of the upper 
of the humerus upon the lower has taken place. But this discrepancy is much 1 
marked in some animals than in others; for example, it is less so in Cholap" er | 
* Since my paper was read, I find that Professor Owen has anticipated me in this term. In the first volume of his 
“Comparative Anatomy and Physiology of Vertebrates’ (just published), at page 176, he speaks of " = 
(ulnar) tuberosity.” 
