XXIII 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 
Fic. 408.—Psettus sebae, from the West Coast of Africa. x 4. 
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. 
