OF THE MAMMALIAN OSSICULA AUDITUS. 381 



But the stapes of Semnopithecus assumes to perfection the type almost constant in the 

 lower monkeys. The head is deep rather than wide, the crura practically quite straight, 

 the hase rather hroad and almost plane, and the aperture much smaller than in the 

 Simiidse. Thus, when we take into consideration all three ossicula in this genus, we 

 see at once that the majority of their salient features ally them, as a whole, to lower 

 genera. The nature of the incus, and the few points given ahove regarding the malleus, 

 show a decidedly high, tendency in Semnopithecus, compared at least with Macacus. 



In the malleus from a large skull of Golobus satanas (PI. LVIII. fig. 8), propor- 

 tionally smaller than the same ossicle in a Semnopithecus of the same size, the head is 

 rather ill-developed and flattened laterally — a condition seen, hut never to so marked a 

 degree, in Macacus and Cynocephalus. But there is a distinct, short, constricted neck, 

 very like that of the last genus, with a well-developed processus brevis ; only the processus 

 muscularis is abortive, and the tip only slightly spatulate. The incus is distinctly higher 

 and narrower than in the genus Semnopithecus ; and its crura arise nearer to each other. 

 Hence, as to these bones, Colobus must take a lower place than Semnopithecus, the ill- 

 developed head of the malleus being apparently a generic peculiarity, and the incus 

 allying it decidedly to succeeding genera. But the well-developed processus brevis, and 

 the still distinct neck, are marked affinities to the genera already considered. 



Cercopithecus (PL LVIII. fig. 9) is central among these Old-world monkeys in its 

 ossicula. The head of the malleus is fairly developed; the articular surface, though 

 shaped as in Homo, assumes the position usually observed in lower animals, the outer 

 extremity lying but little higher than the inner. A trace of lamination, as described in 

 Semnopithecus, exists; the root of the processus gracilis is very thin and fragile. The 

 neck is always extremely short (in C. cynosurus, however, I have found it nearly as long 

 as in S. entellus) ; and the manubrium runs almost in its axis. This is similar in 

 form to that of the last two genera, and bears a distinct processus brevis, never so well 

 developed as in any higher monkeys, excepting Simia. In C. diana it is more prominent 

 than in C. cynosurus or in C. lalandii. The extremity is always spatulate, often dis- 

 coidal (as in a Diana-monkey, of which the ossicula are in the College collection). But 

 there does not seem to be any convexity above the tip, as described with Semnopithecus. 

 A more or less distinct trace of a processus muscularis is always seen upon the inner 

 border of the manubrium*. The incus is very high and narrow in C. cynosurus, but in 

 the other species resembles that of Colobus ; the processus longus is very straight and 

 slender. The stapes is as described with Semnopithecus ; in one from a fine C. diana the 

 base is so broad that the whole bone forms almost an equilateral triangle. 



In Macacus (PL LVIII. fig. 10) the malleus assumes an extreme condition in this 

 group. The head presents a surface flattened laterally, and projecting considerably for- 

 wards. This is best seen in M. nemestrinus and M. erythrceus ; in M. cynomolgus it is 

 nearly as small as in Colobus. There is a trace of lamination and a stout processus 



* This is represented in a sketch of the malleus of O. sabceas in Owen's ' Anatomy of Vertebrates,' vol. iii. 

 fig. 177 c. 



SECOND SERIES. — ZOOLOGY, VOL. I. 3 F 



