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XXVII. On the Communications between the Cavity of the Tympanum and the Palate 
in the Crocodilia {Gavials, Alligators and Crocodiles). 
By Professor Owen, F.R.S. 8fc. 
Received December 20, 1849, — Read February 28, 1850. 
There are three perforations which succeed each other along the middle line of 
the base of the cranium in the Crocodilian Reptiles. The hindmost (Plate XL. 
fig. 1, v), situated in the basioccipital, near the condyle, is the smallest and least con- 
stant in size and existence : it gives passage to a vein, which traverses a vertical canal 
in the bone homotypal with the vertical vascular canal that opens upon the under 
surface of the bodies of the vertebrae of the trunk. The next foramen in advance, e, 
is larger and on a lower level ; it is constantly present and is regular in its size and 
position : it perforates the fore part of the basioccipital close to the basisphenoid. 
The third or anterior foramen, n, is the largest, and opens on a still lower plane : it 
is formed entirely by the pterygoids, which it perforates in a forward direction, and 
is the posterior aperture of the nasal passages. 
There exists a difference of opinion as to the nature of these latter foramina, and 
especially as to the function of the middle foramen, e, viz. that which perforates the 
basioccipital close to the basisphenoid. Cuvier describes it in his celebrated chapter 
on the Osteology of the Crocodile, in the last volume of the 'Ossemens Fossiles,’ 
p. 78, 4to, 1824, as leading to “a canal which traverses the body of the sphenoid, 
and terminates by two branches opening into the ‘sella turcica,’ and, at p. 133, he 
refers to it in the cranium of the ‘ Gavial de Caen’ (Teleosaurus cadonensis, Geoffroy), 
as an arterial foramen (‘ le trou des arteres’).” The continuators of Cuvier, in the 
posthumous edition of the ‘Lecons d’Anatomie Comparee,’ t. ii. p. 523, describe the 
foramen in question more accurately, as leading to a canal which bifurcates as it 
ascends; one of the branches traversing obliquely the body of the sphenoid, whilst 
the other perforates the basilar part of the occipital, and opens into the cavity of the 
internal ear. They do not state where the branch terminates which traverses the 
basisphenoid*, nor v/hat passes through either canal. 
In the description of the tympanic cavity of the Crocodile-I', no mention is made 
of this communication, or of the Eustachian tube, wliich is described in the Saurians 
* I use here, and throughout this paper, the English equivalents of the French phrases defining tlie bones 
of the Crocodile's skull, according to the table of synonyms. No. 1, in my work ‘ On the Archetyjie of the 
Vertebrate Skelton,’ 8vo, 1848. 
t Op. cit., tom. iii. p. 512. 
3 x 
MDCCCL. 
