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Proceedings of the Royal Society of Edinburgh. [Sess. 
preceding, was similarly attached to the lip. These processes were brittle, 
and if the tympanic was roughly handled they easily broke and the malleus 
became detached and lost. The Incus had a body, 8 mm. in diameter, on 
which were two concave articulations for the malleus. A short, sharp 
process projected from the posterior surface and nearly reached the roof of 
the tympanic cavity. From the inner aspect sprang a longer curved process 
which, together with the body, measured 14 mm. ; at its free end was an 
oval facet for the stapes. The Stapes had a corresponding facet on its head, 
from which a pair of short relatively thick legs arose, to end in the plate- 
like foot of the stirrup. A very thin layer of bone passed between the legs 
and was pierced by a minute foramen. The stapes, 11 mm. long, occupied 
a funnel-shaped depression in the inner or petrosal wall of the tympanum, 
and its oval foot, 8 mm. in diameter, was attached to the fenestra ovalis 
of the cochlea (fig. 4). 
As the fusion of the malleus with the tympanic gave to the Cetacea 
an exceptional character as compared with other mammals, I may state 
the species in which I have noted this arrangement. In the whalebone 
whales I saw it in Balcena mysticetus and biscayensis, in Balcenoptera 
musculus, sibbaldi, borealis, rostrata, and in Megaptera longimana. In 
the toothed whales I saw it in Hyperoodon, Phocsena, Globicephalus, 
Grampus, Delphinus, Tursiops, and apparently in Monodon. In several 
other species in the University Museum the malleus was not in place and 
had not been preserved. It should be stated that previous observers have 
noted the fusion of the malleus with the tympanic in certain species. Knox 
saw it * in Balcenoptera sibbaldi and rostrata ; Carte and Macalister spoke 
of it in B. rostrata as a process of the tympanic bone, from the margin of 
whose centre it projected; Dwight described it in B. musculus as co-ossified 
with the tympanic by a processus longus, which had a deep groove anteriorly ; 
Lillie in B. musculus as fused to the inner edge of the lip of the tympanic. 
Different views have been expressed regarding the morphology of the 
processes of the malleus. By some, the process fused with the tympanic 
lip has been regarded as the manubrium or handle of the bone. Possibly 
the two parallel processes which I have figured in B. sibbaldi were only a 
twin-like arrangement of this process. Others, again, have considered the 
fused process to be the long slender (gracilis) process of the human anatomist. 
Buchanan, whilst recognising the handle as always attached to the outer 
* Knox, Catalogue , pp. 14, 21, who named the species Balcena maximus borealis and 
minimus ; Carte and Macalister, op. cit. ; Dwight in Memoirs of Boston Society of Nat. Hist., 
vol. ii. ; Lillie, Proc. Zool. Soc. London , 1910 ; Turner in Marine Mammals and in Memoir 
on Balcena biscayensis , Trans. Roy. Soc. Edin ., vol. xlviii., 1913. 
