2 THE VOYAGE OF H.M.S. CHALLENGER. 



Male. Ft. in. 



From the tip of the nose along the back to the root of the tail, . .33 



Length of tail, . . . • • • • . 1 8J 



Female. 



From the tip of the nose along the back to the root of the tail, . .27 



Length of tail, . . . . • • • .14 



The male had manifestly been received in a very putrid state, but its long immersion 

 in strono- spirit had considerably improved its condition. The female was in an admir- 

 able state of preservation, and it is consequently from it that the majority of the 

 drawings have been taken and the description framed. A special interest is attached to 

 the anatomy of this animal, from the very prevalent belief that the genus of which it is 

 the sole member is rapidly becoming extinct. Thus Owen, 1 writing in 1842, speaks of 

 it as a species " whose term of existence seems fast waning to its close." 



The Cuscus was obtained in New Guinea, and was presented to Sir Wyville Thomson, 

 while on a visit to Queensland, by Mr. Sheridan of Maryborough. 



In my examination of the intrinsic muscles of the marsupial manus and pes, I was 

 met by a somewhat puzzling multiplication of the elements. To explain this, and at the 

 same time connect the condition with that found in other animals, I was induced to 

 extend my inquiries upon this point into Mammalia generally. The results of this 

 investigation I have incorporated with the present report. 



Myology of the Anterior Limb. 



Shoulder and upper arm. — Before entering upon a description of the muscles of the 

 shoulder, it is necessary to refer to the condition of the clavicle. In the Cuscus and 

 Phascogale this bone is well developed, and, stretching from the sternum to the scapula, 

 has a distinct attachment to both. In the Thylacinus, on the other hand, the clavicle is 

 exceedingly rudimentary. It is merely represented by a narrow curved rod of bone, 

 about two inches in length, embedded in the substance of the cephalo-humeral muscle, 

 and in no way attached to the acromion. To the sternum it is joined indirectly by an 

 ill-defined fibrous band or raphe. 



Trapezius. — This muscle has a similar origin in the three animals. It springs from 

 the occipital crest, from the spinous processes of all the cervical vertebrae, and from the 

 spines of the seven anterior dorsal vertebrae. From this extensive origin its fibres extend 

 in the form of one unbroken muscular sheet, and converge towards the shoulder. Here the 

 posterior and greater part of the muscle is inserted into the spine of the scapula (PI. I. 

 fig. 5, tr.), and the root of the acromion process, whilst the anterior portion sweeps over 



1 Transactions of the Geological Society, 1842, vol. vi., 2nd series on the Phascolotherium. 



