OF THE MAMMALIAN OSSICULA AUDITUS. 437 



and manubrium ; the lamina is very wide and thin. Here it may be observed that in all 

 the above characters this ossicle resembles the same in Sorex. It has not either the 

 well-formed head of Talpa or the vertically wide articular surface and short neck of 

 Myogale. The processus gracilis is broader at the root than in the Shrew ; and in form, 

 being of equal breadth for the greater part of its length, it resembles the same in the 

 Phalangers and other Marsupials *. 



The manubrium is rather short, it is broad at the base, with a very prominent ex- 

 ternal angle, not produced into a processus brevis. Its outer aspect, though extremely 

 narrow, is nevertheless separated from the much-flattened sides by distinct borders ; the 

 extremity is very faintly dilated, so as to appear styliformf. The whole manubrium is 

 separated from the neck by a very deep constriction, so as to be readily broken off. 

 Erom this constriction, on the inner aspect, arises a very prominent globular process, 

 attached by a very narrow peduncle. 



It is as difficult to decide whether in this animal the above is the analogue of the true 

 globular apophysis of the Shrew and Gymnura, or whether it is the processus muscu- 

 laris, as is the case in the malleus of Myogale. In Condylura the process certainly 

 points backwards, as in Myogale,- like the globular apophysis of Gymnura ; but (likewise 

 as in Myogale) the tendon of the tensor tympani is attached to the root of the process 

 in the Star-nosed Mole, which may hence be either considered the homologue of the 

 processus muscularis, or else as the homologue of the globular apophysis made use of, so 

 to speak, by the tensor -tympani tendon as a point of attachment. 



The incus in Condylura is almost identical in character with that of Talpa in the 

 smallness of its body, the extremely slight development of its processus brevis, and the 

 large deeply channelled processus longus. 



Chrysochloris possesses a malleus of a perfectly unique pattern (PL LXII. figs. 9, 10). 

 Otto and Rudolphi first appear to have observed the extraordinary development of the 

 head of the malleus ; but the former repeated the error of the latter, who took the 

 enormously enlarged head for a fourth ossicle. Hyrtl discovered their mistake, and 

 settled the true nature of the singular pear-shaped prominence from the malleus of the 

 Cape Golden Mole. The error of the first two anatomists above named must have arisen 

 from their having attempted to remove the ossicle by pulling at its manubrium with 

 forceps without enlarging the aperture of the meatus ; in doing so the bone is readily 

 broken. If the malleus be extracted by chipping away some of the bone forming the 

 prominent convexity in the temporal fossa behind which the enlarged head is lodged, 

 then there is no fear of its breaking at the neck ; but it cannot be drawn safely through 

 the meatus. When removed entire, it may be examined separately with little fear of 

 damage, as it is by no means fragile. 



The head of the malleus of Chrysochloris is extremely elongated, so as to be over a 

 quarter of an inch in length. Hyrtl describes it as pyriform, although, being rather 

 thick and cylindrical at its root, convex behind, and slightly concave in front, it 



* This process is united, partly by bone, to the tympanic ring in the adult Condylura. 



f P have never found the extremity of the manubrium to be absolutely styliform in any mammal except in its 

 modified homologue in the Dolphins. 



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



