XXVII. On the communications between the cavity of the tympanum and the palate in the crocodilia (gavials, alligators and crocodiles)

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Abstract
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 con­stant 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 vertebræ 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 tie Caen’ Teleosaurus Cadonensis , Geoffroy), as an arterial foramen (‘le trou des artères’).” The continuators of Cuvier, in the posthumous edition of the ‘Leçons d’Anatomie Comparée,’ 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, whils 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 what passes through either canal.

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