158 ON THE MORPHOLOGICAL CONSTITUTION OF 



a pair of separate triangular-curved bony plates, which, 

 limiting the size of the right and left pneumatic orifices, brings 

 these into communication with the posterior ethmoidal air-cells 

 or sinuses. These " sphenoidal turbinated bones," or " bones 

 of Bertin," in contact along their outer margins, and outer part 

 of their inferior aspects, with the sphenoidal processes of the 

 palate-bones, constitute the upper elements or suspensory- 

 extremities of the inverted arch, completed by the meeting of 

 the palate-bones themselves in the posterior part of the mesial 

 line of the palatal vault. The right and left pterygoids are 

 attached, as a pair of actinapophyses, to this arch. They pass 

 off backwards and outwards from the posterior margins of the 

 perpendicular plates of the palate-bones, and abut in the 

 embryo against the upper and fore part of the mandibular 

 arch, retaining in the tympanic processes of their adult 

 form indications of their early connection with that arch. 

 The most important secondary connection of the pterygoids 

 in the human adult is with the pterygoid processes of the 

 post-sphenoid ; and it is this sphenoidal connection which is 

 most frequently repeated in the animal series. 



I shall not enter at present into the question of the 

 probable existence of " bones of Bertin " in the Mammalia 

 generally ; nor inquire whether the separate orbital pieces of 

 the palate-bones in the herbivorous Cetacea, according to 

 Cuvier, and the separate anterior portions of the pterygoids 

 of the young dolphin, as described by Meckel and Eapp, may 

 be indications of the upper elements of the palatal arch ; but 

 pass on to the consideration of the palatal arch in the lower 

 Vertebrata, in which the two elements of which it appears to 

 consist on each side are distinctly developed. 



Tlie Palatal Arch and Pterygoids in the Bird. — The bone 

 hitherto considered by all anatomists as the vomer of the bird, 

 is a more or less elongated narrow plate, the margins of which 

 are bent upwards so as to convert its upper surface into a 



