104 



Mr. Alb an H. G. Dor an on the [June 15^ 



characters of the neck and manubrium and of the whole stapes it re- 

 sembles the other genera of this group. Cercopithecus comes next, the 

 head of the malleus being well developed and prominent ; but its incus is 

 generally square-bodied or high and narrow. In Colohus and Cercocehus 

 the head of the malleus is almost as flattened and comparatively ill- 

 developed as in Macacus, and the incus is similar. In Cynopiiliecus and 

 CynocepJialus the flattening of the head of the malleus and shortness of 

 its neck and other characters already referred to are as marked as in 

 Macacus, and there are no distinctions of the slightest importance be- 

 tween the ossicula of those three genera. In the shortness of the neck 

 and form of the incus the Old- World monkeys resemble or tend more 

 towards the Cebidse than to Man. 



The Platteehini di:ffier considerably in their ear-bones from the Old- 

 World monkeys, and chiefly in the complete or practical absence of the 

 neck of the malleus in all genera excepting Ateles, and the peculiar shape 

 of the neck in that genus. The Hapalidse have mallei which approach 

 in type the corresponding ossicle in the Lorises (Nycticebidse), and the 

 stapes, by the partial fusion of its crura, reverts to a condition frequent 

 among the Edentata and Marsupialia. Such fusion may be seen both in 

 Hapale and Midas, but is not constant. 



Whilst Ateles difers from all the other Cebidse in its malleus, Cehus 

 closely resembles that genus in having a similar incus ; but in the absence 

 of neck to the malleus it rather resembles Mycetes. In the high narrow 

 incus Pithecia agrees with Mycetes. 



Among the LEMrsin^ the ossicula of the Galagos, Nycticebidae, and 

 Proioitliecus differ hardly at all from the type of the smaller Cebidse. In 

 Lemur the neck of the malleus, and often a trace of the processus brevis 

 mallei, reappears ; and in that genus and the Indrisinse there is a bony 

 canal between the crura of the stapes not observed in the Galagos and 

 Lorises or in Tarsius. Whilst retaining certain points of resemblance 

 to Lemur, the ossicula of Chiromys decidedly remind the observer of the 

 same bones in certain Eodents, especially the Castoridse and Sciuridse. 



Among the Caeniyoea the auditory ossicles of the Tissipedia differ 

 completely in character from those of the Pinnipedia. 



The ossicula of the terrestrial flesh-eaters bear on the whole a strong 

 general resemblance to one another ; still .they present some interesting 

 points of distinction in the more typical families. These distinctions 

 are mostly to be found in the malleus. The presence of a lamina of 

 thin bone between the neck of the malleus and the processus gracilis is 

 a constant character, except in Herpestes and its allies ; and there is 

 always a processus muscularis for the tendon of the tensor tympani, 

 except in the Bears, as Hyrtl has observed. 



Putting aside the TJrsidae, which are at once readily distinguished 

 from all other families by the absence of that process, the more typical 

 divisions present certain salient distinctions in the malleus. In the cats 

 and dogs the muscular process is long, slender, and curved : but in the 



