108 REPORT— ] 877. 



the cervical vertebras, and the spines of the seven anterior dorsal vertehra3, has a 

 somewhat complicated insertion. The posterior and greater part is inserted into 

 the scapular spine ; the anterior portion sweeps over the head of the humerus and 

 the clavicle, and is inserted differently in each of the three animals. In the Cuscus 

 a very few of the fibres — those constituting the anterior free margin of the muscle 

 — are attached to the clavicle ; the others pass down and fuse with the acromial 

 and clavicular portions of the deltoid. In the Phascogale the insertion of this por- 

 tion of the trapezius is precisely similar, with the exception that none of its fibres 

 enter the acromial deltoid, all join the clavicular part of that muscle. In the 

 Thylacme the humeral division of the trapezius passes over the rudimentary clavicle, 

 and some of its fibres mixing with the muscles attached to that bone, it ends 

 entirely in the clavicular deltoid. 



Acromio-trachelien (the omo-atlantic of Professors Haughton and Macalister). — 

 In the Cuscus and Phascof/ale this muscle is double ; in the Thylaeme it is single. 



In the Cuscus and Phascogale the muscle consists of two distinct fleshy bands, 

 which from their position ruay be called the acromio-trachelien superior and the 

 acromio-trachelien inferior. In both cases they arise from the transverse process 

 of the altas, but in the Cuscus the upper muscle derives an additional slip from the 

 transverse process of the axis. They are inserted into the acromion process and 

 spine of the scapula. In the Cuscus the two muscles fuse at their insertion, and 

 occupy the whole length of the scapular spine. In the Phascogale they are separate 

 throughout, but the upper muscle fuses near its insertion with the rhomboid 

 muscle. 



In the Thglac.ine the muscle is single. It arises from the transverse process of 

 the altas, and is inserted into the lower half of the scapular spine and into the 

 posterior border of the acromion process. 



Ckido-oceipital. — This muscle is present both in the Cuscus and Phascogale, but 

 it is absent in the Thylacinc. 



It is a very narrow slip of muscle in the Cuscus, and being closely applied to the 

 upper margin of the cleido-mastoid it is not at first apparent. Posteriorly it is 

 unattached to the sternal end of the clavicle in close apposition with the origin of 

 the cleido-mastoid ; anteriorly it is attached to the occipital ridge at the same level, 

 and between the stemo-mastoid and trapezius. 



In the Phascogale it is a well-marked muscle, distinct and separate from the 

 cleido-mastoid throughout its whole extent. Its attachments are the same as in 

 the Cuscus, but as it approaches the occiput it fuses with the anterior margin of the 

 trapezius. 



Subclavius. — In the Cuscus and Phascogale this muscle presents nothing worthy 

 of special notice. In both it is very strongly developed, and in both it arises from 

 the cartilage of the first rib, and expanding is inserted into the outer half of the 

 clavicle by fleshy fibres. In neither dors it extend beyond the outer end of the 

 clavicle towards the acromion process or supraspinatus fascia. 



In the Thylacinc it has the same origin but a very different insertion. We trace 

 it to the supraspinatus fascia, and through the medium of this it is inserted into 

 the spine of the scapula. 



Deltoid. — In the Cuscus the scapular and the clavicular portions of this muscle 

 are separate above, but they are united at their insertion into the humerus. The 

 former is much the larger of the two. It arises from the acromion process, from 

 the entire length of the scapular spine, and from the fascia covering the infraspinatus 

 muscle. As the acromial fibres pass downwards they are reinforced by those fibres 

 of the trapezius which in man are inserted into the acromion process. The 

 clavicular portion of the muscle arises from the middle third of the clavicle, and it 

 receives those fibres of the trapezius which in man are attached to the clavicle. 

 The two portions of the deltoid, thus reinforced, converge as they proceed down- 

 wards, and fusing with each other, and to a certain extent also with the lower part 

 of the pectoralis major at its insertion, they are inserted into a well-marked deltoid 

 impression on the upper and outer aspect of the shaft of the humerus. 



In the Phascogale the deltoid is broken up into three distinct factors, quite 

 separate from each other except at their insertion. This triple constitution of the 

 muscle is due to the acromial fibres passing down as a narrow band, apart from 



