OF THE MAMMALIAN OSSICULA AUDITUS. 407 



X. In the Procyonidse the manubrium of the malleus is long, its outer aspect as 

 narrow as in the Viverridse, and the processus muscularis as ill developed as in that 

 family. The processus hrevis of the incus is shorter (except in Nasua) than in the already 

 named groups, excepting the Weasels. 



XI. In Bassaris and JElurus the malleus has the same characters as in Procyon. The 

 lamina is very wide, as in most Bears ; but the processus muscularis appears never to 

 be absent. The processus brevis of the incus is very short. 



XII. In tbe Ursidse the manubrium is long, with a very narrow outer surface ; the 

 processus muscularis is very short, or quite obsolete, the lamina wider than in the Cats 

 and Dogs. The processus brevis of the incus is very short, and the stapedial process 

 long and divergent from the body. In the latter ossicle it is allied to the Weasels, Pro- 

 cyonidse, Bassaris, JElurus, and to the Eared Seals. 



XIII. In all the Seals the ossicles are of very dense consistence ; and in all but the 

 Otariidse they are very large, absolutely and proportionally. 



XIV. In the Otariidse the ossicles are small ; the incus is of the ursine type, but the 

 malleus and stapes decidedly phocine. 



XV. In Trichechus the malleus resembles that of Phoca, excepting that the manu- 

 brium is extremely short. The incus is very like that of the Phocina, but the stapes 

 like that of Macrorhinus. 



XVI. In the Cystophorina, the ossicula of Cystophora are very similar to those of 

 Phoca ; but in Macrorhinus the malleus and incus more resemble those of the Steno- 

 rhynchina, whilst the stapes is of the Walrus type. 



XVII. In the Stenorhynchina the malleus has a very large head, and a manubrium 

 almost as short as in Trichechus ; the body of the incus is very bulky. The stapes is of 

 slender make compared with the same in the Walrus and Macrorhinus. Lobodon and 

 Stenorhynchus are very similar in their ear-bones. 



XVIII. In the Phocina the head of the malleus is excavated, and the articular sur- 

 face of a distinctive form, as in all the Pissipedia. The neck is not as long as in Cysto- 

 phora cristata, but longer than in the other Seals; the manubrium is of moderate 

 length. The incus has often a special process, articulating with a corresponding deve- 

 lopment from the malleus. The stapes has rather stout crura ; an aperture is constant, 

 being never effaced as in Trichechus and Macrorhinus. Neither is that ossicle nearly 

 so bulky as in those genera ; but it is a little stouter than in the Stenorhynchina. 



The Ossicula op the Rodentia. 



This order is remarkable for extreme variety in the form of the auditory ossicles in 

 different families : nearly every type of malleus may be observed among Rodents ; a 

 peculiar kind of ankylosis between that ossicle and the incus is exclusively found in 

 certain groups of this order; and there is likewise great variety in the form of tbe 

 stapes. 



To study the peculiarities of the ossicula of the Sciurid^, a set should be selected from 

 a skull of one of the fine large foreign species, such as the Malabar Squirrel (Sciurus 



3 I 2 



