CHAP. XXIII ACANTHOPTERYGII 651 
OPISTHOMI 
PEDICULATI 
PLECTOGNATHI 
SCLEROPARE/ 
| DISCOCEPHALI 
Ophidiidee 
BATUALAP 
Blennitde 
GOBITFORMES 
JSUCULARES 
SCOMERIFORMES 
Acanthurtdxe 
Scarier 
TANM/IOSOM! 
Serrapidie PYG LEORHOMEL 
PERCIFORMES 
ACANTHOPTERYGII 
BOVOAR 
HAPLOMI 
Fic. 399.—Diagram showing probable relationship of the various groups to one 
another. 
Primary shoulder-girdle composed of a perforate scapula and a coracoid ; of 
the four or five pterygials, or basal bones of the pectoral fins, only one or 
two are in contact with the coracoid ; ventral fins thoracic. 
Rays of the caudal fin not strongly forked at the base; hypural usually 
with a basal spine or knob-like process on each side; epipleural bones 
usually inserted on the parapophyses or on the ribs; dorsal fin usually 
with strong spines; caudal peduncle rarely much constricted 
I. PERCIFORMES. 
Rays of the caudal fin strongly forked at the base, embracing a considerable 
portion of the hypural, which always bears a basal spine ; epipleural bones 
usually inserted on the centra or on the parapophyses, rarely on the ribs ; 
dorsal spines feeble or detached; caudal peduncle much constricted ; 
seales usually very small or absent . A . II. ScomprirorMes. 
