16 



Compared with thc ribs of the Chim])Hnzec, those oi the Activc 

 Gibbon are slight in form : compared \vith those of a Baboon, they 

 are strong. 



A reference to the dorsal column of the table of vertebrcC given 

 above \vill show that the number of ribs varies considerably in the 

 genus Hylobates. 



Section III. — Ot the Foue Extremities. 



The clavicles, which from their great length throw the scapulse 

 far backwards, and give great breadth to the shoulders, are flattened 

 horizontally, have but little marks of tendinous attachment, and pre- 

 sent neither the double curvature of Man nor the straightness of the 

 Orang Utan, but a simple gentie curvature outvvards. 



The scapulae are of a more lengthened shape than in the human 

 subject, from which they also differ in having the aspect of the gle- 

 noid cavity far less laterally and more upwardly directed, in the 

 upper edge of the bone rather desceuding than ascending from this 

 cavity, in the convexity instead of concavity of the humeral edge, 

 and the far greater acuteness of the inferior angle. 



The pcculiarities to be remarked in the humerus are its extraordi- 

 nary length, reaching to just above the head of the femur, its slight- 

 ness of form, and the general weakness of its elevations. The tuber- 

 cles at the superior head are very small. Its tvvist oceurs about 

 one-third from the upper extremity of the bone, as in Man. The 

 external apophysis can scarcely be said to exist ; the internal is 

 present. 



The fore-arm is remarkable for its length (which is yet more ex- 

 traordinary than that of the arm), for the slenderness of its form, 

 and for the extent of the interosseous space formed by the great 

 outward curvature of the radius : by this lašt character the Gibbon 

 is distanced from Man, but approximated to the Orangs. The greatest 

 distance of the radius from the ulna oceurs about one-third of the 

 length of the fore-arm from the superior articulation ; not near the 

 inferior head, as in the human skeleton. The olecranon of the ulna 

 appears neither so broad nor so strong as in Man. 



In this specimen the fore-arm is t\vo inches longer than the arm. 

 In the adult Hoolock the diiFerence is about Ii inch ; in the Hylo- 

 bates concolor about Ž-į- inches. These proportions correspond \vith 

 those of the Orangs, but are at variance with the human, "vvhere the 

 arm is about two inches longer than the fore-arm. Now it is re- 

 markable that in the inimature Gibbons the proportion of these 

 parts has been found to resemble the human (see Dr. Harlan, ubi 

 supra). Not only then are the skuUs of these monkeys more anthro- 

 poid in youth than maturity, but likevvise the proportions of the an- 

 terior extremities. Retrogression with advancing age from a superior 

 to an inferior type of organization is not so common in nature as the 

 converse. 



The carpus of the Agile Gibbon appears to contain the šame eight 

 bones as in Man ; not eleven, as Daubenton statės that the Hylobates 



