ACANTHOPTERYGII 



667 



covered, an extreme exaggeration of the " Ctenoid " type. The 

 mouth is very protractile, and the vertebrae are only 22 or 23 in 

 number. Antigonia, with a single species found at remote points 



FIG. 408. Psettus sebae, from the West Coast of Africa. x i. 



in the Atlantic, Pacific, and Indian Oceans, is probably allied to 

 Capros, with which it is believed to be connected through the 

 fossil genus Proantigonia, from the Upper Miocene of Croatia. 



Fam. 27. Chaetodontidae. Closely allied to and evidently 

 derived from the more generalised types of the Scorpididae, 

 differing in the attachment of the gill-membranes to the isthmus. 

 Post-temporal more or less firmly united with the skull, some- 

 times indistinctly bifurcate. Mouth small ; palate toothless ; 

 soft portions of vertical fins usually covered with scales ; ribs 

 usually strong and blade-like ; body short and deep. 



A large group of about 200 marine carnivorous fishes from 

 the tropics, mostly of small size, remarkable for their singular 

 forms and markings and brilliant coloration. They are par- 

 ticularly abundant about volcanic rocks and coral reefs. 



