396 MR. ST. G. MIVART ON THE ANATOMY OF ECHIDNA HYSTRIX. 
the arm represent the extensor surface and muscles of the leg, and that the same repeti- 
tion exists, speaking generally, between the flexor surfaces and muscles of the two limbs’, 
It is also, I believe, all but universally received that the costal surface of the scapula, 
with the subscapular muscle, is represented in the hind limb by the internal surface of 
the ilium and iliacus. Professor Huxley? alone, so far as I am aware, has suggested 
that the last-named muscle is the homotype, or serial homologue, of the supraspinatus, 
comparing the ilium to the remarkable scapula of the Monotremes, in which, as Pro. 
fessor Owen pointed out?, the apparent anterior costa is really the margin of the spine, 
and the supraspinatus fossa has come to be placed on the internal or costal surface of 
the scapula. 
Dr. G. M. Humphry, in his * Treatise on the Human Skeleton,’ has made a remark- 
able advance towards clearing up this serial homology, still retaining, however, inter- 
pretations with which I cannot agree. At pages 599 and 600 he says, “ The key to the 
exact homology of the upper and lower tims (figs. 7 and 8), I apprehend, is furnished 
by the fact that they are placed at opposite ends of the trunk, and that the apposed 
surfaces of their upper segments have, consequently, been made to correspond with one 
another. The hæmal constituents of the visceral arches upon which they rest are 
modified accordingly. Thus the scapula is inclined backwards, and the ilium forwards; 
the hinder edge of the scapula corresponds with the anterior edge of the ilium ; and the 
rough projection near the glenoid cavity, for the attachment of the long portion of the 
triceps (the extensor of the forearm) corresponds with the anterior inferior spine of the 
ilium, which gives attachment to the rectus femoris, the long portion of the extensor of 
the leg; the coracoid process is homologous with the pubes, the clavicle with the 
ischium. The posterior surface of the femur corresponds with the anterior surface of 
the humerus. The upper flexure in the former bone is backwards, the lower flexure is 
forwards; whereas in the humerus it is just the reverse. The lesser trochanter of the 
femur, which receives the iliacus muscle coming from the inner surface of the ilium, 
looks backwards ; and the lesser tubercle of the humerus, which receives the subscapt- 
laris muscle coming from the inner surface of the scapula, looks forwards. The outer 
and inner surfaces of the two bones respectively correspond with each other: thus the 
great trochanter of the femur and the great tuberele of the humerus are both j 
outwards; the rough space for the great gluteus, which comes from the tuber is chiiand 
sacro-sciatic ligament, is upon the outer side of the shaft of the femur; and the rough 
space for the deltoid, which comes from the clavicle and acromium, is upon the outer 
side of the shaft of the humerus; the rough space for the long adductor muscle, W 
comes from the spine of the pubis, is on the inner side of the shaft of the femur; aP 
the rough space for the coraco-brachialis, which comes from the tip of the coracoid pro 
cess, is on the inner side of the shaft of the humerus; the outer condyle of the fete 
of the 
! ‚Professor Owen does not admit this relationship, but regards the flexors of one limb as the homotypes 2 
cipum of the other. See the first volume of his recently published Comp. Anat. of Vertebrates, vol. i P 
; i oniy since my paper was read that I have become aware of this opinion of the learned Professor. 
See * Medical Times’ for February 1864. 
* Todd’s Cyclopeedia, vol, iii. p. 376. 
