The Squamipinnes 613 
altisstmus, with a very high dorsal, is fossil in the Eocene of 
Monte Bolca. 
The Butterfly-fishes: Chztodontide.—The central family of 
Squamipinnes is that of the butterfly-fishes or Chetodontide. 
In this group the teeth are distinctly brush-like, the mouth 
small, the dorsal fin continuous and closely scaly, and the ven- 
tral fins with one spine and five rays. The species are mostly 
of small size and brilliant and var.ed coloration, yellow and 
black being the leading colors. They vary considerably with 
age, the young having the posterior free edges of the bones of 
i 
Fig. 507.—Butterfly-fish, Chetodon capistratus Linneus. Jamaica. 
the head produced, forming a sort of collar. These forms have 
received the name of Tholichthys, but that supposed genus 
is merely the young of Chetodon. The species of Chetodontide 
abound in rock pools and about coral reefs in clear water. They 
are among the most characteristic forms of these waters and 
their excessive quickness of movement compensates for their 
conspicuous coloration. In these confined localities they have, 
however, few enemies. The broad bodies and spinous fins make 
them rather difficult for a large fish to swallow. They feed 
