554 MR. H. M". KYLE ON NASAL 



in others Keibel * has more recently, in opposition to His t, con- 

 firmed, tliose which concern the formation of" the palate, though 

 he is doubtful about the secondary origin of the internal uares. 



If the conclusions of Hochstetter had been the last word on 

 the matter, it would have been possible to frame an homology 

 between the internal nares of Cynoqlossus and those of the higher 

 Vertebrates. If the latter arise secondarily in ontogeny, then it 

 is probable that at their first beginning they were also of 

 secondary origin, and therel'ore distinct from the primitive 

 internal nares of the Dipnoi. Hence we might have in Cyno- 

 gJossus a glimpse of what may have occurred at a remote period 

 of time, when the air-breathing Vertebrates were but in process 

 of evolution. 



But if Keibel's suggestions (see footnote ;|:) are well-founded, 

 then we must accept, in a modified form, Balfour's view con- 

 cerning the origin of the internal nares as the true one, and upon 

 this no comparison could be made between Cynoglossus and the 

 higher Vertebrates. Morphologically, Cynoglossus would then 

 be perfectly unique, possessing not only the homologues of the 

 internal nares in the morphological sense, but additional organs 

 also which represent the internal nares in the physiological 

 sense. The internal nares of Cynoglossus should then be called 

 " pseudo-nares " or " pseudo-choani," which would emphasize 

 their morphological distinction from the " choani " of the higher 

 Vertebrates, whilst implying their physiological similarity. 



It is of interest to note, in conclusion, that this discovery in 

 the Teleostei of a distinctive peculiarity of the higher Vertebrates, 

 is not without a parallel. Warm blood has been found in the 



* Keibel, F. : " Zur Entwickelungsgeschichte und vergleiehenden Anatomie 

 der Nase u. des oberen Mundrandes (Oberlippe) bei Vertebraten." Anat. Anz., 

 Ed. viii. 1893, p. 473. 



t His, W. : " Die Entwickelung der menschlichen und tierischen Pbysio- 

 gnomieen." Archiv f. Anat. u. Phys. (Anat. Abth.), 1892, p. 399. 



{ In his short paper Keibel concerns himself mostly with the palate and 

 upper lip of the Vertebrates, and it is only secondarily that he throws out 

 suggestions as to the formation of the internal nares. Hence his meaning is 

 not Yery easily determinable, but it seems to be as follows: — The internal 

 nares are homologous and primary structures wherever they appear in the 

 Vertebrate kingdom. They arise from the inner portion of the primitive nasal 

 groove — as described by Balfoui' — but instead of the raaxillffi growicg in 

 between the primitive nostril and nares, it is the " palate " — formed from the 

 median and external primary nasal processes. The Selachii represent, there- 

 fore, the most primitive condition, where the pi-imary nasal groove persists. 



