PEIMATES PEOM MADAGASCAE. 131 



on the outer side of the bicipital " lip " being closely similar in the two bones, though 

 there is in Mesopropithecus a short prominent ridge about 1 cm. in length running 

 down from the lower angle of the greater tuberosity, which evidently has its homologue 

 in the well-marked crest which in the fossil " Lemurs " is continued downwards in a 

 spiral course to join the lower end of the deltoid ridge. The distal end of the bone is 

 imperfect, but its trochlear surface apparently bears more resemblance to that of 

 Propitheacs than to that of Archceolemur . The long, projecting, backwardly-curved 

 outer epicondyle is, on the other hand, strongly suggestive of the corresponding part of 

 the humerus of Archceolemur. 



Lemur. — The humeri, the dimensions of which are given in Table 19, Nos. 16-26, 

 are all referable to the genus Lemur. They are all very similar in size and type, as 

 might be expected from the similarity which we have noticed in the series of skulls 

 of this genus. A detailed description of this bone will not be necessary for my present 

 purpose. It is interesting to note in passing, however, that its straighter shaft 

 tends (text-fig. 32, B) to approximate it to the humerus of Archceolemur. 



The Radius. 



Appended is a table (No. 20) giving dimensions of several types of radius occurring 

 in the collection from Ampasambazimba. Only two of these will be referred to in the 

 present section — those of Megaladapis and Palceopro^pithecus. 



Megaladaj)is. — The radius of Megaladapis (Nos. 1-6 in Table 20) is a long, some- 

 what slender, curved bone (text-fig. 34). The curves of its head correspond exactly 

 with the capitular surfaces of the humeri already described, and with the lesser sigmoid 

 cavity of an ulna to be presently referred to. Its neck is somewhat slender, its tubercle 

 long and much roughened, showing the possession of a powerful biceps muscle. The 

 shaft is widely curved, its centre being some 2 centimetres distant from a chord 

 joining its two extremities. With the exception of this greater curvature and its 

 mere slender proportions, the radius of Megaladaj)is bears a considerable resemblance 

 to that of Man. The interosseous edge has a regular curvature which hardly deviates 

 from a plane bisecting the radial head and passing through the styloid process. The 

 three articular facets for the ulna, scaphoid, and semilunar bones are very similar in 

 shape and disposition to the condition seen in Man. The styloid process is less 

 prominent, and the diverging lines of the inner and outer edges of the distal end of 

 the bones are less abruptly curved than in the human radius. 



It is not, of course, intended to imply by such a comparison that there is any close 

 connection between such an animal as Megalada])is and Man, but merely to point out 

 that types which by their brain-development are removed as far as possible from each 

 other in the Primate series have both retained similar features in their limb-structure. 

 At the end of his text-book on ' Morphology and Anthropology,' Professor Duckworth 

 concludes that the balance of evidence indicates that, were the material still available, 



VOL, xviii. — PART II. No. 10. — May, 1908, t 



