ICHTHYOPHIS 143 



that while the essential organs of respiration 

 have changed from gill - clefts to lungs, the 

 muscular and skeletal mechanism of respiration 

 has remained practically unchanged. 'It may be 

 added that Ichthyophis is a good swimmer but 

 tries to get out of water as soon as possible, 

 creeping with difficulty on a free surface by 

 serpentine jerks, but moving easily through 

 narrow crevices where its contact requirements 

 (i.e., stereotropism) are satisfied. Similar obser- 

 vations with regard to the respiratory movements 

 have been made by my friend Professor Graham 

 Kerr (in litt.} on the Dipnoan fish Lepidosiren. 1 



FlG. 12. Head and fore-body of Ichthyophis glutinosus from above, 

 to show the collar-like respiratory region. At the sides of 

 the head in front of the eyes is the pair of peculiar retractile 

 tentacles. 



The fact that in the course of the substitu- 

 tion of lungs for gills the respiratory movements 



1 For a discussion of the nerve-supply see ]. Graham Kerr, 

 " Note on Swim-Bladder and Lungs," Proc. Roy. Physical Soc., 

 Edinburgh, vol. xvii., 1908, pp. 170-174. 



