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



malleus of the Muridse, where the lamina is broad and semitransparent as in the 

 Carnivora. Its general resemblance to the malleus of the Marsupialia is very evident. 



The incus of Pteropus has a well-formed body, not deeply excavated. The processus 

 brevis is distinct, but very short ; the stapedial crus is rather long, and ends in a pedun- 

 culated almost discoid Sylvian apophysis. In relation to other animals its characters 

 are negative. 



The stapes has a small head with slender crura; the posterior quite straight, the 

 anterior generally a little curved *. They do not diverge so much as in Man ; but there 

 is a free aperture not occupied in the recent condition by any intercrural canal. The 

 base is rather narrow horizontally, and almost plane towards the vestibule ; it projects 

 but little beyond the insertion of each crus. 



The stapes of Pteropus must be considered of rather central type, for it shows no sign 

 of any tendency towards the columelliform stapes of most Marsupials ; but its crura do 

 not diverge as in the anthropoid Apes and Man, nor even to the extent seen in Ruminants 

 and Carnivora. It most resembles the stapes of those Insectivora where the crura are 

 not widely bowed to admit the passage of a bony canal, or the same ossicle in the Mice. 

 This variety of stapes, with its straight crura, diverging btit little, and its consequently 

 narrow base and narrow but distinct aperture, lies between the carnivorous type, where 

 the aperture is larger, but the crura as straight, and the form seen in Didelphys, where 

 the crura are free throughout, yet leave a very narrow aperture between them. 



I have experienced great obstacles in the study of the ossicula of the insectivorous 

 Bats, as in museum specimens the bones of the auditory region are frequently lost in 

 macerating the skull ; still more generally are the incudes and stapedes wanting, and 

 the delicate malleus is frequently mutilated. Nevertheless I have succeeded in procuring 

 specimens of at least the latter ossicle from Bats belonging to all the chief divisions of the 

 group, nor, judging from duplicates, does there seem to be great variety among them. 



In studying the malleus of Asellia tridens, as an example of the Bhinolophid^;, a 

 very strong general resemblance to the same bone in the Shrew (Sorex) may be observed 

 at a glance. It is absolutely necessary, in studying the ossicula of the smaller Chiroptera, 

 to place thoroughly clean white specimens upon a piece of black paper ; they may then 

 be viewed by direct illumination under the microscope. A 1-inch object-glass is suffi- 

 ciently strong for this purpose. 



The head of the malleus in Asellia tridens f (PI. LXII. fig. 20), though small com- 

 pared with the area of the entire ossicle, as in all laminated mallei, is well formed 

 and convex. The articular surface is rather deeper cut than in Pteropus ; but the facets 

 are of similar character, the upper and anterior being the larger. The neck is narrow, 

 longer even than in Sorex, and resembles its homologue in the Shrew in being sharply 

 bent midway between the head and the manubrium. At the apex of this angle I 

 find, projecting internally, a curved process (pm), remarkably like a second process 

 (acpm). 



* Hyrtl (op. cit.) states that the crura "in Pteropus edulis and P. vulgaris [sic] are convergent before their insertion 

 into the base." This is not the case in the College specimens. 



f In Mr. Dobson's ' Monograph of the Asiatic Chiroptera,' Asellia is reduced to a subgenus of Phyllorh'ma. 



