Prof. Eschricht on the Gangetic Dolphin. 173 



innermost pair is extremely delicate, and appears only in the 

 hindermost part of the palate ; it belongs to the vomer, being no 

 doubt always connate, as is the case generally with the side 

 plates of a perfect vomer along the median line. 



A difficulty arises in explaining these bones : we have only two 

 distinct pairs to represent the three palatal bones, namely the 

 bones of the upper maxillary, the palatal and the pterygoid bones. 

 Cuvier intended apparently to solve the question by exclusively 

 designating the nasal plate of the hindmost, the pterygoid bones, 

 and the two other plates, the palatal bones. He says, " En dessous 

 il y a aussi des particularites tres-diffe rentes des autres especes. 

 Les palatins occupent en longueur un beaucoup plus grand espace, 

 et vont jusqu'a s'articuler en arriere avec les temporaux qui s'arti- 

 culent aussi en un point avec les frontaux, de sorte que les parietaux 

 ne touchent pas aux palatins. Les apophyses pterygoYdes ou os 

 pterygo'idiens forment, comme dans les autres dauphins, la plus 

 grande partie du contour des arriere-narines, mais il me parait 

 pas qu'elles se replient pour tapisser en dessous les sinus places 

 sous les narines ; et meme ces sinus, dans toute leur longueur, 

 n'ont point de paroi inferieure osseuse et ne sont fermes en des- 

 sous que par des membranes ; les parois inferieures des palatins 

 laissant une grande solution de continuite dans toute leur Crete 

 inferieure. Les sinus communiquent amplement dans le squelette 

 avec le reseau osseux de la face inferieure de cretes maxillaires." 

 (p. 299.) 



Contrary to this view, according to which the said bones, con- 

 sisting of three plates, which occupy the greatest part of the palate 

 and extend quite to the temporal cavities, are made to represent 

 by one of the plates the palatal bone and by the other the zygomatic 

 bone, I must insist on their being altogether pterygoid bones. 

 This opinion may, perhaps, be thought untenable, inasmuch as the 

 zygomatic bones cannot be supposed to have such a large extension, 

 least of all to reach so far as into the palatal cavity, where they seem 

 to occupy the place of the large wings of the sphenoid bone ; 

 especially if the opinion, current in all the newest and best zoolo- 

 gical manuals, and among them in that of Stannius*, that the 

 pterygoid bones simply correspond to the inner wings of the sphe- 

 noid bone, is adopted. But it will be admitted, at all events, that 

 it is rather the pterygoid than the palatal bones, which should be 

 considered as occupying the place of the large wings of the 

 sphenoid bone in the temporal cavities ; and in the next place it 

 should be borne in mind, that I have shown in the whalebone- 

 whales, and expressly in the Baltenoptera rostrata, that the ptery- 



* Lehrbuch, &c. (Manual of the Comparative Anatomy of Vertebrate 

 Animals). Berlin, 1846, 8vo, p. 366, note 14. 



