REPORT ON THE MARSUPIALIA. 9 



lip of the bicipital groove of the humerus. In Thylacine it is inserted in common with 

 the latissimus dorsi through the medium of a fibrous arch (vide p. 5). 



The subscapularis is well marked in all, and presents the usual attachments. 



According to Meckel the infraspinatus is smaller than the supraspinatus in the 

 Marsupialia generally. The accuracy of this observation is shown by Professor Macalisti t, 1 

 who gives the definite information that "the supraspinatus is larger in the Wombat, 

 Phalanger, Perameles, Sarcophilus, and the Opossum ; in the Giant Kangaroo they are 

 about equal, while in Bennett's Kangaroo the infraspinatus is the larger." 



Cuvier and Laurillard do not figure a teres minor in the Phalangista cavifrons 

 (pi. clxxviii. fig. 1), but they represent a very strong teres minor in the Giant Kangaroo, 

 (pis. clxxxvii. and clxxxviii.). This hardly agrees with Professor Macalister's description. 1 

 This author states that it is not separable from the infraspinatus in the Macropus 

 giganteus, Phalangista vidpina, Perameles lagotis, and Didelphys Virginia na ; in the 

 Wallaby, however, it is distinct, and in the Wombat and Tasmanian Devil it is represented 

 by "a fascial band." 



Deltoid. — In the discus the scapular and clavicular portions (PL II. fig. 4, c.d.) of this 

 muscle are distinct above, and separated from each other by a considerable interval. The 

 scapular part is much the larger of the two ; it arises from the acromion process, from the 

 spine of the scapula in its entire length, and from the fascia covering the infraspinatus 

 muscle. As the acromial part proceeds downwards, it is joined on its superficial surface 

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

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

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

 reinforced by trapezial fibres the two portions of the deltoid converge as they pass down- 

 wards towards a salient ridge jutting out from the antero-external aspect of the shaft of 

 the humerus, at the junction of its upper and middle thirds. The scapular deltoid is 

 inserted into the outer surface of this ridge, whilst the clavicular deltoid is fixed to 

 its summit, where it is fused to a certain extent with the insertion of the pectoralis major. 



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

 acromial, and spinal — 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 the fibres which take origin from the spine of the scapula. The 

 humeral portion of the trapezius joins the clavicular deltoid alone, and has no connection 

 whatever with the acromial part of the muscle. The insertion is the same as in Cuscus ; 

 the ridge in the shaft of the humerus, however, is not so strongly marked. 



In Tlii/Iacinus (PL I. figs. 4 and 5) the deltoid is in two parts, — scapular (s.d.) and 

 clavicular (c.d.), — and these are separate from each other both at their origin and at 

 their insertion. The scapular deltoid is much the larger of the two, and it has a similar 



1 Loc. cit., p. 3. 



(ZOOL. CHALL. EXP.— PART XVI. 18S1.) Q 2 



