OF THE MAMMALIAN OSSICULA AUDITUS. 431 



in the Zoological Gardens in the summer of 1875. The tendon of the tensor tympani 

 was on both sides attached to the elevation referred to above ; yet a similar tubercle may 

 be seen in other mammals where a processus muscularis also exists. The great size and 

 peculiar development of this ossicle seems to mask all features which might relate it to 

 any other Order in particular. 



The malleus is as large in E. africanus as in E. indices ; but in the former it is of 

 somewhat lighter make, and the neck is not so broad nor so abruptly bent, while the 

 manubrium is longer. 



The incus of the Elephant has a well-developed body, much deeper posteriorly than in 

 front, where it is excavated for the articular surface. The crura are both short ; the 

 processus brevis diverges but little from the body, and is rather slender' for the bulk of 

 the whole bone ; the processus longus is more divergent, and turns up very slightly at 

 the tip, which bears a small, round, flat and sessile Sylvian apophysis. This bone, 

 taking even its large development into consideration, cannot be referred to any type 

 prevailing among the Ungulates. An approach to it is seen in many Rodents, espe- 

 cially as regards the much greater divergence of the processus longus compared with 

 the posterior crus. 



The stapes in Elephas indicus (PL LX. fig. 36) is quite triangular ; the head is 

 well developed, and bears a tubercle on its posterior aspect for the stapedius tendon ; the 

 posterior crus is quite straight the anterior is slightly curved ; the base is broad, and 

 coDvex towards the vestibule ; it projects considerably in most specimens beyond the 

 insertion of the posterior crus. 



In a single specimen of the stapes of E. africanus, in the College collection, the head is 

 broad, but shallow, and both crura are quite straight ; the bone is triangular, but trun- 

 cated at the apex (fig. 37). 



The peculiarities of the Ungulate ossicula may thus be summarized : — 



I. In this Order the central * laminated type of malleus is the rule ; the processus 

 muscularis is generally present, but is not often of any length ; the incus is rather large, 

 and variable in form ; the stapes has a broad head, and is sometimes quadrilateral. 



II. In the Equidse the malleus is most generalized ; the head is well developed, and 

 the lamina almost obsolete. In the Rhinoceros and Tapir the malleus is of a very low 

 type, almost recalling that of the higher Marsupials. The stapes in all Perissodactyla is 

 triangular, with a wide head. 



III. In the Tylopoda the malleus possesses characters seen both in the Artiodactyla 

 and Perissodactyla, the incus is of peculiar form, the stapes is triangular. 



IV. Among the Artiodactyla the Suidae are distinguished by the production forwards 

 of the head of the malleus and its deep articular surface, even in the larger species. The 

 incus has a very square body, with short crura ; the stapes is quadrilateral. Hippo- 

 potamus resembles the Pigs, excepting that the stapes is perhaps more triangular. 



V. In Tragulus the incus precisely resembles that of Sus, but the malleus and stapes 

 are like the same in the smaller Antelopes. 



* My reasons for using this term when speaking of the laminated malleus will be found in the description of the 

 mallei of the Marsupials. 



3m 2 



