520 PJROr. T, W. BRIDGE OK THE 



In their account of the air-bladder of iV^. Pallasii, Cuvier and 

 Valenciennes (4. pp. 139-141) make no mention of the existence 

 of a series of branched diverticula similar to those which fringe 

 the ventral margins of the caudal prolongations of the air-bladder 

 in N. horneensis ; neither do these authors refer to the extreme 

 tenuity of the inner walla of these portions of the bladder, or to 

 their attachments and relations to the caudal skeletal elements^ 

 nor to the existence of vacuities in the closely related inner walls- 

 of the caudal caeca, by which the cavities of the two cseca freely 

 intercommunicate. 



In their description of the caudal portion of the bladder in 

 N. Pallasii, Cuvier and Valenciennes (op. cit. p. 139) remark : — 

 " II existe sur la surface externe des cornes un organe singulier, 

 comme glanduleux, divise par un nombre considerable de filets 

 blanchatres, anastomoses entre eux en petits lobules, que Ton ne 

 pourrait separer par la dissection qu'avec beaucoup de peine. 

 Get organe, qui couvre presque tout le has de la corne, ne depasse 

 guere la moitie de sa longueur." 



Xo trace of any such gland-like structure could be detected in 

 N. horneensis ; and as no organ of a similar character is known to 

 be associated with the external surface of the air-bladder in any 

 other Fishes, it is impossible to hazard even a conjecture as to its 

 nature in N. Pallasii. 



In their description of the abdominal and anterior portions of 

 the air-bladder, Cuvier and Valenciennes apparently failed to 

 note the skeletal attachments of the organ, or the general 

 tendency of the bladder to lose its external fibrous coat wherever 

 its walls enter into intimate relations with the cranial or vertebral 

 elements of the skeleton. The unsymmetrical subdivision of the 

 abdominal section of the bladder seems also to have escaped their 

 notice. 



The account given by Cuvier and Valenciennes of the mode of 

 termination of the auditory caeca and their relations to the mem- 

 branous labyrinth in Notopterus Pallasii is so different from 

 my own observations on Notopterus horneensis, that I venture to 

 quote their remarks in extenso. 



After describing the extension of the air-bladder towards the 

 cranium, it is stated : " De la elle donne deux cornes qui s'engagent 

 dans I'interieur de la boite cerebrale sous les mastoi'diens, en 

 passant entre I'os et le sac de I'oreille. Ces cornes s'avancent 



