OF THE MAMMALIAN OSSICULA AUDITUS. 427 



the processus brevis is twice as long as the antero-internal ; and the articular surface, 

 well to the front, is of necessity wide. The processus brevis is as long and cylindrical 

 as in Ovis, and much curved outwards ; the processus " longus " is not so long, but it 

 stretches out further than in the Sheep, and does not turn up so sharply near the Sylvian 

 apophysis, which is similar in form. In the foetus of a calf at the sixth week the body 

 is about as well developed, proportionally, as in an adult domesticated Sheep. 



Taken as a whole, the Ox has the best- developed incus of all the Artiodactyla, inas- 

 much as the body is in all directions larger than even in Sus, where the crura are charac- 

 teristically short, whilst those processes in Bos are even longer than in Sheep and 

 Antelopes (where the body is shallower), and as long as in the Deer (where it is generally 

 very shallow and broad). 



The stapes of the adult Ox is absolutely oblong. The head is very broad, with a pro- 

 minent tubercle for the stapedius tendon, which latter is partly ossified. The crura are 

 quite parallel, or even nearer together at the base than the head in very large spe- 

 cimens ; they are well channelled towards the aperture ; the anterior is very thin and 

 straight, and a little longer than the posterior, which is thicker; the base is very stout, 

 and projects well beyond the crura. The whole bone is only an extreme modification of 

 the form seen in Ovis ; indeed in the fetal calf that bone is still trapezoidal, or almost 

 triangular, the head being less broad, and hence the crura nearer together at their 

 origin. 



In the adult Zebu (Bos indicus) the ossicula are more slender than in the Ox ; the 

 manubrium of the malleus is not so boldly curved ; the stapes is even more oblong than 

 in B. taurus ; its crura are very long and close together. 



The ossicula of the Burrhel (Ovis naJwor) are more like those of a new-born lamb than 

 those of a full-grown domestic sheep. The body of the incus is shallower, though the 

 crura are as long ; nor is the stapes so quadrilateral as in O. aries. 



In the adult Goat (Capra) the malleus has an articular surface as wide as in Ovis, and 

 hence not so wide or so plane as in Bos. The manubrium is distinctly curved, almost as 

 much as in the Ox in C. ibex, less so in C. hircus, C. megaceros, and C. cegagrus, judging 

 from specimens in the College collection. The body of the incus is sometimes shallow in 

 this genus ; but in the skulls of large goats it becomes as high as in the adult Sheep. 

 The posterior cms is not very long ; the anterior is sharply bent, as in Ovis. But even in 

 large adults the stapes remains triangular, though the head is always thick, and the crura 

 a distinct distance apart at their origin ; they diverge considerably towards the base, 

 which is very wide and thick, projecting beyond their insertions, and is quite plane 

 towards the vestibule. The crura are almost of equal thickness ; but the anterior is 

 rather the longer. 



In the Chamois (Rupicapra tragus, PI. LXI. figs. 22—34) the articular surface of the 

 malleus is wider than in Ovis or Copra, and almost as wide and as level as in Bos ; but 

 the manubrium is slender and almost straight, as in the Antelopes. The incus resembles 

 the full-grown Sheep's in the development both of its body and crura ; and the stapes is 

 of the same trapezoidal form. 



