352 SHOULDER-GIRDLE IN MONOTREMES. 



which did not, however, communicate with any branches distri- 

 buted to the arm from the brachial plexus. The " lateral 

 cutaneous nerve of the thorax " was present and communicated 

 with the 3rd, 4th, 5th, 6th intercostal nerves, and also supplied 

 the P. quartus. It came off a cord formed by the viii. cervical 

 and first dorsal nerves, and it ended by breaking up into numerous 

 branches, which were distributed to the abdomino-huineral 

 pauniculus. 



Fiirbringer discusses the snpracoracoid nerve in his paper, " Zur 

 vergleichenden Anatomie der Schultermuskelu " (pp. 718-719). 

 He draws attention to the fact that in Sauriaus, where there is no 

 true supraspinatus muscle, the snpracoracoid nerve pierces the 

 pectoral girdle through the foramen coracoidenm, and supplies the 

 supracoracoid muscle. In Mammals, however, the suprascapular 

 nerve, which comes from the same division of the brachial plexus, 

 pierces the scapula through the incisura (foramen) scapulae, and 

 supplies the supraspinatus and infraspinatus muscles, there being 

 no supracoracoid muscle present. Lastly in the Ornithorhynchus, 

 where there is neither foramen coracoideum or foramen scapulte, 

 the nerve trunk answering to the N. supracoracoideus and supra- 

 scupularis proceeds to the anterior part of the space between the 

 coracoid and the scapula, and divides into a ventral and a 

 dorsal branch ; the ventral branch then supplies the M. supra- 

 coracoideus (M. epicoraco-humeralis) ; while the dorsal branch 

 supplies the Mm. supraspinatus and infraspinatus, " er.sterer ist 

 ein unzweifelhaftes Homologon des N". supracoracoideus der 

 Amphibien, Reptilien und Vogel, letzterer stimmt im Wesentlichen 

 vollkommen mit dem N. suprascapularis der placentalen und 

 marsupialen Sangelhiere iiberein. Nach diesem Verhalten muss 

 zwischen N. supracoracoideus und N. suprascapularis eine gewisse 

 Homologie statuirt werden. Diese Homologie ist aber keine 

 complete, denn der N. supx'acoracoideus versorgt ventrale, 

 der N. suprascapularis dorsale Muskeln : der erstere hat also 

 niihere Beziehungen zu den Rr. inferiores des Plexus brachiali^, 

 der letztere zu den Rr. superiores." 



