THE BEXTHAL 



219 



and pomacentrids (Dascyllvs, Fig. 48a; and Glyph idodon) . Species of 

 the percoid genus Serranus and some labrids may resemble each other 

 in their elongate elliptic body form, long, uniform dorsal fin, spotted 

 or vertically banded body with many striped head markings, and the 

 rounded or slightly concave tail fin. Families in which a uniform 



Fig. 49. — Reef fishes with similar shape: a, Holacanthus tricolor, an angel fish; 

 and b, Microspathodon dorsalis, a pomacentrid. After Jordan and Evermann. 



coloration is usual contain fishes with distinct patterns in the East 

 Indies, as in the banded Sytiaptura zebra and the spotted muraenids. 

 The silver coloration, otherwise so widespread, is very rare among 

 coral reef fishes. 83 Other fishes show convergent adaptation in which 



Fig. 50. — Reef fishes with teeth fused into a beak: a, Diodon hystrix, a 

 porcupine fish, and b, Sparisoma aurojrenatum, a parrot fish. After Jordan and 

 Evermann. 



the teeth are consolidated into a beak, enabling them to bite off small 

 branches of coral. Among these are the pomacentrids (Fig. 48a), the 

 sparids (Fig. 506), and the suborder Plectognathi with the trigger 

 fishes (Batistes, Fig. 48c), the trunk fishes, the puffers (Fig. 50a, 



