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the maxillary bone, if I am correct in my assumption, the palatine 

 being the entopterygoid and the transverse the ectopterygoid. In 

 Hatteria punctata (Xo. 26), on the contrary, the so-called palatine has 

 every appearance of being the breathing -valve bone pushed backward 

 so that it lies opposite the posterior half of the maxillary, the ento- 

 pterygoid being represented in the long anterior process of the so- 

 called pterygoid. 



Further evidence as to the possible persistence and importance 

 of the maxillary breathing valve seems to be given in Brauer's state- 

 ment (No. 7, p. 495) that in the Gymnophionae the palate plate is 

 developed from the anterior, inturned end of the embryonic fronto- 

 nasal process of the animal. As the premaxillary must develop in 

 that more dorsal portion, of this same process, that later becomes 

 the anterior edge of the mouth cavity, the anterior, inturned end of 

 the process would be a mucous fold that would have exactly the re- 

 lations to the premaxillary that a maxillary breathing valve should 

 have. As no secondary palate plate, in the sense in which that term 

 is ordinarily used, is found in the Gymnophionae, it is evident that 

 this embryonic breathing valve, if it be such, must coalesce with the 

 primary roof of the mouth cavity, as it does in Polypterus. A com- 

 parison with Polypterus might accordingly give a definite solution of 

 this question if Brauer had only mentioned the bones that are later 

 developed in this inturned, anterior end of the fronto-nasal process of 

 the Gymnophionae. This will doubtless appear in his later works, 

 but for the moment one is in doubt as whether it is the palatine 

 plates of the premaxillaries, alone, that are here concerned, or both 

 those i)lates and the so-called vomers and palatines. 



In Wiedersheim's (No. 46) descriptions of certain of the Gymno- 

 phionae the so-called palatine bone seems certainly to be the homo- 

 logue of the posterior half of the maxillary breathing-valve bone of 

 Polypterus, and its relations to the so-called maxillary of the animal 

 are exactly those of the posterior half of the maxillary breathing-valve 

 bone of Polypterus to the so-called maxillary of that fish. The so- 

 called vomer of the Gymnophionae might then represent the anterior 

 half of the breathing-valve bone, the internal nostril having partly cut 

 the breathing-valve bone in two parts and being in process of passing 

 backward between them. The palatine processes of the maxillary and 

 premaxillary bones of the Gymnophionae would then, alone of the bones 

 on this part of the roof of the mouth, belong to the primary palate 

 plate, and the process of the premaxillary would be the homologue of 

 the Teleostean vomer; a supposition that receives much support in 



