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



narrow. There is always a bony canal between the crura of the stapes. This is seen in 

 the Indrisinse as well, but does not appear to exist in Galago. 



VII. In Chiromys the ossicula are large, and their affinities indistinct. The malleus 

 has a much flattened head and a trace of processus brevis ; in most respects it is of the 

 rodent type. The incus is of a somewhat peculiar shape ; the stapes has curved crura, 

 a character seen in the higher monkeys, but also in many of the Sciuromorpha. 



The Ossicula of the Caunivoka. 



The Eissipedia are almost as remarkable for the very trifling variations in the ear- 

 bones of the different families, genera, and species as the Pinnipedia are for the boldly 

 defined individual characters of all three ossicula in closely allied genera. The study of 

 these bones in the latter suborder is rendered all the lighter on account of their great size. 

 Yet while the Pinnipedia maintain, in the malleus at least, a certain adherence to the 

 common and most typical form of ossicle, the Pissipedia possess a type of malleus 

 unusual except among certain Ungulates and Rodents. 



The Pissipedia must first be considered ; and the study of their ossicula shows that 

 distinctive features of any clear value in classification are chiefly confined to the malleus, 

 the variations in the form of the incus being more limited, although of interest in some 

 families. 



The divisions of the suborder used here are those given by Plower* (P. Z. S. 

 1869, p. 4). 



The typical malleus of a fissiped carnivorous mammal may thus be described : — It has 

 a small head, with a deeply cut articular surface, of which the facets are divided by a deep 

 well-marked groove ; the neck is thin, long, cylindrical, and more or less sharply curved, 

 bearing on its inner side a muscular process for the tendon of the tensor tympani. The 

 manubrium forms with the neck an angle seldom over 100°; it has an angular pro- 

 jection at the outer side of its base, which may be dignified by the name of processus 

 brevis, although never developed to the extent seen in Man. It is narrow laterally ; 

 but the side towards the membrana tympani is constantly separated from the two other 

 sides by sharp borders, and is often very broad. 



But the great and conspicuous feature is the broad lamellar expansion between the 

 head and neck, on the one hand, and the very slender processus gracilis, which often 

 appears as merely a thickened lower border of that bony lamina, undoubtedly a minor 

 modification of the condition existing to an extreme degree in the Hedgehogs, Shrews 

 and Bats. This is observed to a corresponding extent in the Ruminants and larger 

 Muridse. 



The incus in the Pissipedia is always small in proportion to the malleus, directly con- 

 trary to what obtains with the Seals. Excepting extreme shortness of the processus 

 brevis in some families, there are few distinctions of importance between the incudes of 

 the various members of this group. The same applies to the stapes ; and such slight 

 differences as exist will be noted in the description of individual genera or species. 



* In his paper " On the Value of the Characters of the Base of the Cranium in the Classification of the Order 

 Carnivora, and on the Systematic Position of Bassaris and other disputed Porms." 



