136 ON THE HOMOLOGIES OF CERTAIN MUSCLES 



many birds there coexists, with a subscapularis, a 'coraeo-bra- 

 chialis superior ' (no. xvii. Sehoepss), which takes origin from the 

 visceral surface of the coracoid bone and from the same aspect of 

 the coraco-clavicular membrane. The tendon of this muscle may 

 fuse with that of the subscapularis ; and the bicipital muscle thus 

 formed may receive its nerve-supply from a single nerve : but this 

 nerve has never been observed by me to be the same as that which 

 supplies the ' coraeo-brachialis inferior ' (no. xvi. Sehoepss), any 

 more than the nerve of the obturator internus is ever the same as 

 that of the obturator externus. But it is plain that the coraeo- 

 brachialis superior must represent the obturator internus, and the 

 subscapularis the gluteal muscle, which, as mentioned at p. 130, 

 is so closely united with that obturator. 



Neither can I coincide with the late Edinburgh Professor's com- 

 parison of the teres minor and infraspinatus to the gluteus minimus 

 and medius — first, because I cannot but think that the musculus 

 iliacus internus minor (see p. 134) is homologous with the teres 

 minor, and, secondly, because I cannot consider the innervation 

 of these upper-limb muscles to be in any way homologous with 

 that of the glutei. The spinati and glutei do, it is true, re- 

 semble each other in attaining their greatest development in 

 mammals; and the so-called 'gluteus maximus ' and 'medius' of 

 the Crocodilidse (Dr. Hair, 'Journal of Anatomy and Physiology,' 

 Kov. 1867) may be seen, by their innervation from the anterior 

 crural, not to correspond to the similarly named muscles of mam- 

 mals. But concomitant variation within the limits of a single 

 class does not make two sets of muscles, with essentially different 

 insertion and innervation, to be serially homologous. 



Pew anatomists would now deny that the os pubis is the homo- 

 logue, not of the clavicle, but of the praecoracoid ; but though I 

 have myself accepted the comparison of the iliacus to the spinati, 

 I should not so positively dissent from Professor Goodsir's com- 

 parison of it to the deltoid as I do from his other comparisons here 

 specified. 



But I may be permitted, perhaps, to say that the recti abdominis 

 can scarcely be considered to form, as Professor Goodsir ranks them 

 as forming, a class apart from the external and internal obliqui ; 

 for the arrangement of these muscles, as seen for example in the 

 common fowl and the common pigeon severally, seems to me to 



