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angles of the manubrium. In the Dasyures, Opossums, Phalangers, 

 and Petaurists, the manubrium is compressed and elongated, and the 

 clavicles are joined to a process continued from its anterior extremity. 

 The small clavicles of the Kangaroo have a similar connection. 



" The cartilages of the true ribs, (which frequently become ossi- 

 fied in old Marsupials) are articulated as usual to the interspaces 

 of the sternal bones ; the last of these supports a broad flat cartilage. 



" The clavicles are relatively strongest and longest in the burrow- 

 ing Wombat, weakest and shortest in the Great Kangaroo. In the 

 latter they are simply curved with the convexity forwards, and mea- 

 sure only two inches in length. In the Wombat they are upwards 

 of three inches in length, and have a double curvature ; they are ex- 

 panded and obliquely truncate at the sternal extremity, where the 

 articular surface presents a remarkably deep notch : they become 

 compressed as they approach the acromion, to which they are at- 

 tached by an extended narrow articular surface. In the Koala the 

 clavicles are also very strong, but more compressed than in the 

 Wombat, bent outwards in their whole extent, and the convex mar- 

 gin formed, not by a continuous curve, but by three almost straight 

 lines, with intervening angles, progressively diminishing in extent 

 to the outermost line which forms the articular surface with the 

 acromion. In most of the other Marsupials the clavicle is a simple 

 compressed elongated bone, with one general outward curvature. In 

 the genus Perameles there are no clavicles. 



" The scapula varies in form in the different Marsupiata. In the 

 Petaurists it forms a scalene triangle, with the glenoid cavity at the 

 convergence of the two longest sides. In the Wombat it presents a 

 remarkably regular oblong quadrate figure, the neck being produced 

 from the lower half of the anterior margin, and the outer surface 

 being traversed diagonally by the spine ; which, in this species, 

 gradually rises to a full inch above the plane of the scapula, and 

 terminates in a long narrow compressed acromion arching over the 

 neck to meet the clavicle. In the Koala, the superior casta does not 

 run parallel with the inferior, but recedes from it as it advances for- 

 wards, and then passes down, forming an obtuse angle, and with a 

 gentle concave curvature to the neck of the scapula ; a small process 

 extends from the middle of this curvature. In the Potoroos the upper 

 casta is at first parallel with the lower; but this parallel part is much 

 shorter ; the remainder describes a sigmoid flexure as it approaches 

 the neck of the scapula. In the Great Kangaroo, the Perameles, 

 Phalangers, Opossums and Dasyures, the whole upper casta of the 

 scapula describes a sigmoid curve, the convex posterior portion of 

 which varies as to its degi-ee and extent. 



" The subscapular surface is remarkable in the Perameles for its 

 flatness ; but presents a shallow groove near the inferior casta. In 

 most other Marsupials it is more or less convex and undulating. 



" In the Great Kangaroo the supraspinal fossa is of less ex- 

 tent than the space below the spine, and the spine is inclined 

 upwards. In the Perameles and Dasyures the proportions of the 

 supra and infra spinal surfaces are reversed, and the whole spine 

 is bent downwards over the infratpinal surface. In the Potoroos 



