618 DR. ROLLESTON ON THE HOMOLOGIES OF CERTAIN 



totalis secundus of birds does not by any means invariably receive fibres from the coracoid • 

 it does receive such an accession in the Sparrow-Hawk, but it does not do so in the Pigeon 

 (Columba livia) for example ; it may (as seen in great simplicity in the Emu and Apteryx) 

 have a mesoscapular factor actually joined to its tendon, and inserted so as to be one in 

 function with it, and it may be considered, therefore, to be essentially a sterno-prsecoraco- 

 scapular muscle. The sternal factor is lost in the Ostrich (Strut/do camelus), and in the 

 Rhea (Rhea Americana). Similarly the muscle figured at eh, fig. 3, from the Crocodile, 

 is simply a « prsecoraco-scapularis," with one head arising from the anterior surface of the 

 expanse of bone constituted by the confluence of scapula and coracoid in front of the 

 glenoid cavity, and with a second which joins the first on its mesial border as it passes 

 round from the internal surface of the scapular, and is inserted into the outer tuberosity 

 of the humerus, in close connexion with the upper edge of the great pectoral. In the 

 descriptions given of this muscle, both in the Crocodile and in the Ornithorhynchus, it has 

 been confounded with the deltoid It is, however, shown by its innervation to be sepa- 

 rate from it in nature ; and its insertion lies between the insertions of the deltoid 

 externally and that of the pectoralis major internally. This muscle has a single tendon 

 in the Sparrow-Hawk, with three muscular heads converging upon it. In the Galli- 



(Gallus gallinaceus and Fhasianus Colchicus) the levator-humeri appa- 

 consists of three muscles, distinct both in origin and insertion, and innervated 



Galli- 



birds 



from two distinct sources. The largest of the three levator muscles of the 



y extensive origin from the sternum ; but, as is the 



the 



humerus has 

 the Pigeon also, it has no distinct accession of fihres from the coracoid ; but from the 

 coracoid on its inner aspect, from the coraco-clavicular membrane, and from a small 

 portion of the sternum a lesser levator humeri arises, which is inserted, after passing 

 through the coraco-scapular canal and over the coracoid pulley, together with the tendon 

 ~ -water levator, between the point of insertion of this muscle (which is a little 



lower down and more externally placed) and that of the great pectoral to if, inner side. 

 With the tendon of the greater pectoral depressor that of the lessor levator is very 

 closely connected as is that of the epicoraeo-kumeral ot the Crocodile ; and it - J : 



™JE !T„ e .l,! le PUUey Mran S em ^ which converts cooperation into antagonism 



as passing to the single lerator 



Thirdly, the small muscle which has been described 

 tendon of the Sparrow-Hawk from the mesoscapula 



5 



of that hird, has in the Galli 



mof and i'nl?, nS1V , e f^' ** & ^P 8 ™* 6 inSCTtion " Jt «**» '*»» «" "Pl- 



srsrrst scrap . scapuia ' * *• fr ° m th ° " —««n« - of ***«*, s» 



tne ligament which passes along the inner asnecr nf *l,„ „„ i , * *i 



mesoscapula to the eoracoid and IZ « • coracoscapulnr canal from the 



coracoid itself Z^T^' ^ lmiOTni ost and uppermost scrap of the 



nternal "a ' ^f Y* I""" ****** to that of the -"*■ <^atol Uraerl, 

 m usX The " del", \ *? ° f ^ «*»* *"** In «» common Goose tU. 



tt smaLt 5T °* "^ " fused *» » ™ «» «• «™ -HP- 



. ,! 1 "* ^ ' °! the F ° WI ; and ™ *™ thus an intermediate *. between the 



muscle of the same 



i. *n i ,. ~ " w **■**> *\j uaxlio clU Hill 



^ fi i, mSert , IOn ° f the ^-to-apparatus of the Fowl and thc single tendon of the Hawk 



. . externus " of the »»»«»#»• 



origin and insertion, with the ant 



It will he oh™™ + k . *iT , r u lfle * owl ana the sin gle tendon of the Hawk. 

 1 loor^T: ! 1^1 *» eXte — " ° f the common^owl corresponds, both 



pra3glenoid head of the " epicor 



