128 ON THE HOMOLOGIES OF CERTAIN MUSCLES 



found in Mr. Parker's work 'On the Shoulder-Girdle and Sternum,' 

 at pp. 7, 59, and 83. 



Professor Huxley's view (which has been adopted by Mr. Mivart, 

 and a similar one to which, I am informed by Professor Turner of 

 Edinburgh, was entertained by his predecessor Professor Goodsir), 

 as to the homotypical relationship of the subscapularis and teres 

 major, not to the iliacus and psoas, but to the middle and smallest 

 gluteus, is a third point for discussion, and one which does not 

 admit of being decided quite so cursorily as the two I have already 

 glanced at. For the acceptance of this apparent paradox, it is 

 necessary first to accept the principle that 4 the true homology of a 

 muscle is to be determined by its insertion (see Mivart, ' Trans. 

 Linn. Soc' vol. xxv. pp. 398 and 400). To this principle I should 

 give a general assent, without forgetting that we may find ex- 

 ceptions to it, such as the insertion of the pectoralis major of the 

 sparrow-hawk into both tuberosities of the humerus, such as the 

 occasional insertion, in the way of corollary to this first exception, 

 of the pectoralis minor into the outer tuberosity of that bone, or 

 such, thirdly, as the insertion of the psoas of the crocodile on the 

 outer, while the iliacus is inserted on the inner side of the femur. 

 In these cases, however, rudiments at least of the primitive insertion 

 in the shape of aponeurotic bands will ordinarily be left remaining, 

 as if to indicate that it has been, so to say, not by an arbitrary 

 transference, but by a gradual lateral extension that the alteration 

 of the point of attachment has been effected : and the essential 

 character of a muscle may be considered to be as little affected by 

 these transgressions of its ordinary limits laterally, as the essential 

 character of a muscle which is ordinarily inserted into the proximal 

 segment of a limb is considered to be affected by its occasional 

 prolongation into a distal segment, by fascia or aponeurosis, which 

 may finally be specialised into a tendon. There are, however, three 

 sets of anatomical facts to which I would draw attention, as they seem 

 to me to make the denial of the homotypical relation of the iliacus 

 and subscapularis, and the ranking of the latter muscle with the 

 glutei, less of a stumblingblock. First, there can be no reasonable 

 doubt that the essential character of the muscle I have called ' epi- 

 coraco-humeral' in the crocodile, is determined by its innervation 

 and by the insertion or wedging in of its tendon on the outer 

 surface of the humerus between those of the pectoralis major and 



