382 MR. A. H. G. DORAN ON THE MORPHOLOGY 



gracilis, of which a great part is persistent in adult Macaques. Although the neck does 

 exist, it is extremely short, especially its anterior wall, the manubrium running almost 

 in its axis. The latter seems to spring from immediately below its articular surface ; its 

 extremity is often quite discoidal ; the processus brevis may be completely obsolete, but 

 it is fairly marked in some species ; the processus muscularis is in the same position as in 

 Semnopithecus, and is generally well developed. 



The body of the incus is always either square or higher than broad ; the anterior 

 segment is nearly as high as the posterior. Hence it approaches (in the first pecu- 

 liarity) the form seen in some specimens from Hylobates, and (in both the above points) 

 many of the Cebidse. Both processes are rather long and slender; the long crus is 

 very straight till close to the tip. The stapes has straight crura and a broad base, as 

 in all the past genera. 



In Cynopithecus (PL LVIII. fig. 11) the head of the malleus is as ill-developed as in 

 Colobus, the neck and manubrium closely resemble the same in the Macaques. The 

 incus has an extremely stout square body ; the anterior segment is very well developed. 

 The crura are very much stouter and shorter than in any Macacus of the same size, 

 and shorter, though of the same thickness as in Cynocephalus. This incus, with its 

 square body and short stout crura, is as different from the anthropoid type, and as 

 strikingly reminds the observer of the shape of the bone in Cebus and Ateles, as the high 

 narrow incus of Hylobates and Macacus diverges from the type of Homo in a direction 

 towards the form prevailing in Mycetes and in other less typical Cebidse. 



The stapes, too, though very similar to the prevailing form in this group ,see Semno- 

 pithecus), has a narrower base ; nor are the crura so far apart as usual. 



In Cynocephalus (PI. LVIII. fig. 12) the characters of the malleus are like those of 

 Macacus, but rather more marked. The head is not so developed in proportion to the 

 size of the bone, is extremely flattened laterally, and projects very sharply forwards. The 

 neck is also extremely shortened, especially in its anterior wall ; the manubrium runs 

 almost in its axis. This process has a very well developed processus brevis, and a sharp, 

 extremely prominent muscular process almost halfway down the inner margin of the 

 handle. 



The incus has a rather shallow body, and very stout crura ; the anterior is rather long. 

 It is clearly of a higher type than in Macacus. 



The stapes of the Baboons does not differ from the common type in this group, and is 

 in outline almost an equilateral triangle. 



In conclusion, it may be said of the Old-world tailed-monkeys : — 



I. That they all depart from the apes and Man, and resemble lower monkeys and 

 most other mammals in the straight and little-divergent crura of the stapes. A pro- 

 cessus muscularis on the malleus is almost constant. 



II. In the distinctly-necked malleus, with a well-formed head, and in the incus, 

 broad between the crura, Semnopithecus approaches the Simiidse, especially Hylobates ; 

 but the stapes is not at all anthropoid. 



III. In Cercopithecus the malleus is nearly as high in type, but the incus is either 

 square-bodied or high and narrow, as in lower monkeys. 



