OF THE MAMMALIAN OSSICULA AUDITUS. 445 



cessus brevis of the incus is well developed ; that crus is smaller in Gymnura and 

 abortive in Erinaceus. 



XL The orbicular apophysis of the Shrews, Daesmans, Myogale, and Hedgehogs allies 

 them to the Muridse, where also the malleus is laminated. 



The Ossicula of the Chiroptera. 



The malleus of JPieropus (PL LXII. figs. 26, 27) is attached to the ring-bike tympanic 

 bone much in the same manner as among the Insectivora and Marsupials. The anterior 

 or upper extremity of that bone is fissured, and the processus gracilis fits into the cleft, 

 beyond which is a flat surface, to which the extremity of the process is ankylosed. The 

 portion of the tympanic external to the cleft is very thick, and it runs over the outer 

 surface of the lamina and neck of the malleus, a distinctive feature not observed in the 

 non-placental mammals or in the Insectivora, the tympanic ring reaching, in those 

 animals, not further backwards than to the root of the processus gracilis. 



The head of the malleus is small, and projects very Little beyond the articular surface, 

 which is placed as much posteriorly as superiorly, and is shallow, but deep vertically. It 

 is distinctly divided into two facets, although they are not separated by a sharp hori- 

 zontal groove ; the upper is larger, and lies a Httle more internally than the lower, and 

 both are faintly convex. The neck is narrow and well curved, as in most laminated 

 mallei ; the lamina is rather narrow, and formed of opaque and brittle, not semitrans- 

 parent, papery bone : the processus gracilis is broad and thin at its root, the lower 

 border being, however, well defined, and the lamina is prolonged upon it ; this process 

 ends in a point as in most Insectivora, not in a foHaceous dilatation as in many 

 Marsupials. 



I have found, in dissecting the ear of a fresh Bat (Pteropus), that the tendon of the 

 tensor tympani is inserted into the point of junction of the neck and manubrium, at the 

 most usual site, in fact, of the processus muscularis, which does not exist ; but there is 

 a distinct prominence close to the manubrium at the place where a large orbicular 

 apophysis is seen in the Shrew (Sores), Mouse (Mm), &c. The relations of that process 

 to the processus muscularis have been already fully discussed in describing the ossicula 

 of the Shrew and other Insectivora. Suffice it to say here, that in Pteropus the rudiment 

 of the orbicular apophysis does not replace functionally the processus muscularis as in 

 Myogale and Condylura. This rudiment is better marked in the College specimen from 

 P. hypomelanus than in that from P. edulis in the same collection. 



The manubrium is slender and rather long, broad at the base and flattened laterally ; 

 in fact, sword-shaped. Its outer and upper angle (not to be confounded with the rudi- 

 mentary orbicular apophysis which pushes it aside) is somewhat blunt, so that no pro- 

 cessus brevis exists; the outer aspect is very narrow, but bordered sharply from the 

 sides, and ends in a distinct spatulate dilatation. 



It is evident that a verdict of " low type " must be passed on the malleus of 

 Pteropus. It has no anthropoid, ceboid, or lemuroid characters. It is not the typical 

 laminated malleus of the Carnivora and the Ruminants. It is decidedly lower than the 



SECOND SERIES. — ZOOLOGY, VOL. I. 3 O 



