OF THE MAMMALIAN OSSICULA AUDITUS. 377 



as horizontally, than in the lower animals, even including the Elephant, as Hyrtl justly 

 observes; but in the Golden Mole (Chrysochloris) and a few other fossorial animals 

 the width of the aperture at the base is proportionally greater, though the head is much 

 nearer the foot-plate. 



The presence of a minute tubercle on the inner side of the head of the stapes does not 

 seem constant in our species. The occasional ossification of a part of the stapedius tendon 

 in Homo is well known ; it is a constant feature in many animals. 



For the most recent minute observations on the anatomy of the human ossicula, the 

 works of Magnus *, Helmholtz +, Eysell %, Rudinger §, Trautmann ||, Urbantschitsch ^[, 

 and others should be consulted. 



The Ossicula of the Simiid^. 



In a set of ossicles from a large mature foetus of a Gorilla (PI. LVIII. fig. 3) the incus 

 much resembles that of Homo, the stapes is not so large as in the human foetus at birth, 

 and the crura are a little more slender and straighter. The tympanic ring from the 

 same foetal Gorilla has a considerable part of the floor of the external meatus already 

 developed, which is not the case in Homo at birth. Both rings are preserved in the 

 College of Surgeons' collection. 



I have examined a single malleus of the adiilt Troglodytes gorilla. It is above 

 the average size of the same bone in Man. The free upper portion of its head is 

 more developed than in Homo or Simla, and is somewhat flattened vertically, at the 

 same time protruding considerably forwards, as in the Chimpanzee. The articular sur- 

 face remains oblique, so that, as in our species, its outer extremity, or the homologue of 

 that extremity in other animals, lies very much higher than does the inner. The 

 outer and upper segment of the articular surface is far larger than the inner ** — another 

 point in which this genus differs from Man and the Orang. The upper and lower facets 

 are saddle-shaped ; the vertical convex ridge is very near the inner margin of the whole 

 surface ; and hence the external, concave, sloping portions of both facets are very wide. 

 A very faint groove divides them, indeed, as in Man ; it is' only relatively that they can 

 be spoken of as two separate facets. This is the case with the remaining Quadrumana. 



The neck is rather short and very narrow ; the size of the head and the length of the 

 handle make it look less developed than it really is. The sigmoid ridge described in 

 Man is well marked. In the mallei from a foetal Gorilla the processus gracilis is very 

 slender, especially at the root. 



The manubrium is very long, resembling in that respect the Orang's, and differing 

 from the rather shorter manubrium of the Chimpanzee and Man. It is somewhat narrow 

 at the root, and well recurved at the tip, which is more thoroughly spatulate in Homo and 



* " Beitrage zur Anatomie des mittleren Ohres," Yirchow's Archiv, vol. xx. j- Op. cit. $ Op. cit. 



§ 'Atlas des menschlichen Gehororgans.' Munich, 1875. 



|| " Der gelbe Fleck am Ende des Hammergriffs,"' Archiv f. Ohrenheilk. vol. xi. 



% ""Zur Anatomie der Gehbrknochelchen des Mensehen,'' Ibid. vol. xi. 



** This condition is not nearly so marked in specimens from new-born Gorillas. 



