GREGORY: FISH SKULLS 



417 



certain scorpsenoids (Figs. 206, 207), the star-gazers (Fig. 246), etc. Finally, in the flat- 

 fishes (Fig. 224) the mouth is twisted during development so as to face more on the upturned 

 side of the body. 



Tube-like prolongations of the preorbital part of the face terminating in small nipping 

 or nibbling mouths are likewise developed independently in different groups. In certain 

 mormyrids the extremely minute nibbling mouth is found at the end of a long decurved tube 

 far beneath the eyes (Fig. 64). Among the tube-fishes (Fig. 105) and their allies the pro- 

 longation of the region between the eyes and the mouth becomes amazingly great. Appar- 



Platysomus 



B / CoccocephalLLS 



Cheirolepis 



Fig. 286. Progressive reduction of jaw-length correlated with forward swing of the auspensorial line (HQ) in palseoniscoids. 

 A. Cheirolepis. After D. M. S. Watson. B. Coccocepkalus. After Watson. C. PerUidus. After Stensio. D. Platysomus. 

 After Watson. 



