OF THE MAMMALIAN OSSICULA AUDITUS. 449 



longation across the lamina. The processus longus of the incus is very long. The stapes 

 is identical in form with that of Vesperugo *. 



Among the EMBALLONTJKiDJi; Molossus obscurus shows in its malleus (PI. LXII. 

 fig. 24) all the typical appearances above described in Asellia ; but the processus mus- 

 cularis in Molossus, as in most Bats, represents the upper process described as existing 

 in Asellia. The orbicular apophysis is not so large as in the last-mentioned genus. The 

 quadrilateral condition of the manubrium is very well marked. 



Among the Phyllostomid^e I fail to find any distinctive characters. In the malleus 

 of Chilonycteris osberni the processus muscularis is very stout and long, and I have 

 preserved the tensor tympani muscle actually inserted into it in a specimen in the 

 College collection ; but the process is the same in position as that in Molossus, hence 

 corresponding to the upper process in Asellia. The reader is referred to the description 

 of the malleus in the latter genus for arguments on the homologies of the two processes. 

 The mere fact of the upper process being found the most constantly throughout the 

 Chiroptera is, as already remarked, in favour of its being the true processus muscularis* 

 the lower being so very rarely found. 



The incus of Chilonycteris has an extremely long processus longus, but the processus 

 brevis is much less developed than in the Bats already described ; this in itself is 

 decidedly a sign of low type. 



In Mormops blainvillii the malleus has a similar character to that of Chilonycteris ; the 

 processus muscularis is in the same position (PL LXII. fig. 23). 



I regret I have been unable to procure ossicula from the crania of Bats belonging to 

 other genera. Sufficient material, however, has been examined to warrant certain definite 

 conclusions on the characters of the ear-bones of the Chiroptera. 



I. In all the Chiroptera the ossicula much resemble those of the Soricidse and allied 

 Insectivora, particularly in the malleus. 



II. In the frugivorous Bats the malleus does not resemble that of Sorex so strongly 

 as does the same ossicle in the remaining section of this Order ;, indeed it approaches the 

 marsupial type in general characters, but bears a strongly marked rudiment of the 

 orbicular apophysis seen in the Shrew. 



III. In all the insectivorous Bats the malleus bears a long, curved processus mus- 

 cularis, and in some genera (at least in Asellia) a process apparently accessory to it. 

 A well-formed orbicular apophysis is constant, the lamina is always wide, and the 

 manubrium is quadrilateral, the outer and inner aspects being sharply bordered off from 

 both the sides. 



IV. The incus in all the Chiroptera has a very short processus brevis and a very long 

 divergent processus longus, as in Sorex and the Marsupials. In this point the Shrews 

 and Bats differ from the Muridse, where the malleus is similar in character to the same 

 ossicle in the former animals. 



V. The stapes is never columelliform, or even approaching that low type, but, on the 

 contrary, the aperture is generally wide; this is partly necessary, at least, for the 



* Prof. Owen describes in Vespertilio noetula " a retention of the columelliform confluence of stapes and incus * 

 (Anat. of Verteb. vol. iii.). 



