FISHES. 293 



Above this bone, and behind the pterygoid there is another large 

 and flat bone (No. 27,) and above the latter, a large one (No. 23,) 

 the same which I have already named temporal; it is articulated by 

 a gynglimus with the two bones of the cranium, which we have men- 

 tioned as corresponding to the posterior frontal (No. 4,) and the 

 mastoidean (No. 12). This temporal furnishes behind an articular 

 tubercle to the principal piece of the opercule (No. 28,) and gives 

 inferiorly an attachment to a bony stile (No. 29,) which supports the 

 branch of the oshyoides, and which represents the styloid bone in the 

 mammalia. 



Behind these three pieces, runs lengthwise the bone (No. 30) 

 which serves as a fixed border for the motions of the opercule; I 

 have named it the preopereule. But there is still between the flat 

 intermediary bone and the preopercule another long narrow bone 

 (No. 31,) which passes partly behind that to which the mandible is 

 articulated, and which forms an angle with the styloid. 



It may be remembered that in birds, the bone which I have called 

 the square bone, and which I consider analogous to the caisse, is arti- 

 culated on one side with the cranium, on the other with the internal 

 pterygoid and the jugal, and gives attachment below to the lower jaw. 

 The functions of that bone are here performed by the four bones just 

 described, not including the preoperculum ; but these four bones are 

 not on this account, dismemberments of the caisse, on the contrary, 

 three of them join it, to assist in some measure in filling up the large 

 space, which was here necessary between the temple and the lower 

 jaw for lodging the branchial apparatus. I believe that I have 

 been enabled to determine them properly by comparisons with lizards 

 and frogs. In lizards, the iguana for instance, or the monitor, the bone 

 which I have thought proper to regard as analogous to the scaly tem- 

 poral, is articulated with the posterior frontal, and the mastoidean ; 

 and to it, is chiefly suspended, the tympanal or bone of the caisse. 

 Let it be supposed that this bone acquired mobility, that it moves on 

 the two bones to which it is immoveably articulated, it will corres- 

 spond to the upper one of the bones we are now examining (No. 23) 

 that which unites the palatine and pterygoid apparatus to the cra- 

 nium. This bone, as I have said, would therefore be the temporal.* 

 On the other hand, we have seen in frogs| a jugal and a zygomatic 

 evidently recognizable, passing from the maxillary to the lower part 

 of the tympanal, and sharing in the articulation of the lower jaw, in 

 which it somewhat reminds us of what occurs in the kangaroo. Let 

 us suppose it to supersede the tympanal of this articulation, in the 

 same manner as the tympanal supersedes the scaly temporal in the 

 other oviparous animals, that it takes entirely to itself, and on the 

 other hand, that it abandons the superior maxillary, retaining no 

 attachment whatsoever with it, we shall then have our inferior hone 

 of the apparatus in fishes (No. 26), that which presents a facet to the 

 for the articulation of the lower jaw. This bone would then be, as I have 



* This is the serrial of M. Geoffroy, the sympleclicum primum of M. Bakker, the 

 square bone of M. Rosenthal, the caisse of M. Bojuims. 

 T See my researches on fossil bones. 



