628 DR. ROLLESTON ON THE HOMOLOGIES OF CERTAIN 



m 



Postscript, Dec. 11, 1868. 



Several memoirs bearing more or less directly upon the subjects treated of in this 



paper have appeared, or at least come into my hands, subsequently to June 14th, 1868. 



First among them I may mention the paper on " Variations in Human Myology," which 



was read June 18th, 1868, before the Royal Society, by John Wood, Esq., F.R..C.S. In 



this paper, as published in the Uoyal Society's Proceedings, vol. xvi. no. 104, will be 



found an excellent figure of that common modification of the pec t oralis minor which 



converts it into a more or less perfect levator humeri, so far as function is concerned. 



But that it was not a morphological equivalent of the pectoralis secundus of the bird 



would have been shown, I apprehend, first, by its relation to the costo-coracoid 



brane, and, secondly, by its innervation. Meckel, in his ' Vergleichende Anatomie,' iii. 



p. 318, speculates as to whether the bird's " pectoralis secundus " is to be regarded as a 



divarication of the great pectoral, or as a specialization of a part of the deltoid. Now, as 



I hold that the pectoralis minor is essentially a part of the pectoralis major, I should say 



that Mr. Wood's figure shows that a levator humeri may be formed in the former of these 



two ways ; and that such a muscle may be formed in the second of these two ways also 



is shown by the history I have given, pp. 618, 619 of this paper, of the smaller levator 



humeri in the Fowl. But that the ordinary levator humeri, s. pectoralis secundus, of 



birds, which coexists with the smaller levator in the Fowl, corresponds, as a matter < 



fact, to the rpicoraco-humeral of the Reptile and the subclavius of the Mammal, is shoTV 



by the history of its relations to surrounding parts, by its nerve-supply, and by the 



history of the development of the great pectoral. Nor does functional correspondence 



enable us to argue to morphological identity here more than anywhere else. 



Secondly, Professor Goodsir's * Anatomical Memoirs' have, since last June, been 

 published under the able editorship of his successor, Professor Turner ; and in the first 

 volume, at p. 452, may be found an exposition of the views of the late great anatomist, 

 alluded to at p. 620 of this paper, as to the -morphology of the muscles of the limbs." 

 \i ith reference to this paper, I would remark that it seems incorrect to class the obtu- 

 rator mternus with the subscapular, because in many birds there coexists, with a 

 ^scapukm*, a « coraco-brachialis superior" (no. xvii. Schoepss), which takes origin 

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

 cla neular membrane. The tendon of this museie may fuse with that of the subscapular ; 

 and the mental muscle thus formed may receive its nerve-supply from a single nerve : 



'I at rr> i as ne r r t ; bserved by me to be the ^ - that **<* 4?^ ^ 



rZZZ T (n °- XVi * Sch ° epSS) ' "* ^re than the nerve of the <*» 



"ZT7 7 "" Same " ^ ° f ^ ° btumt0r **"*• But ^ is plain that the 



^^^ UP Tl ^ ^^ ^ 0UumtW "— * and ^subscapular 

 tiie gluteal muscle, which, as mentioned at ™ ft9i «oo <• u • . , . .. , 



with that obturator. PP ' ^' ^ ° f *" P a P er ' ls s0 closel y umted 



nlfZ Zi I SI?^ the late Ed ^urgh Professor's comparison of the teres 



Z Hank tlST / v '**"• ^^ aad "«*«-** 1-ause I eannot 



Mte^^jrT : t T rnm miM>r (S6e PP" 622 " 624 "*"»> » homologous 



the teres mnor, and, secondly, because I cannot consider the innervation of these 



