XXIII ACANTHOPTERYGII : 693 
serious objection could be raised to their union in one great 
family with a number of minor divisions. 
The character from which the Scleroparei derive their name 
Fra. 423.—Left pectoral arch of A, Sebastes percoides ; B, Scorpaenichthys marmoratus ; 
C, Dactylopterus volitans. cl, Clavicle ; cor, coracoid ; pel, post-clavicle ; p.7, pec- 
toral rays ; ptr, pterygials ; pite, post-temporal ; sc, scapula ; sc/, supraclavicle. 
is subject to many modifications. The second suborbital (the 
third if the praeorbital be regarded as the first) may be merely 
enlarged and prolonged over the cheek towards the praeoper- 
culum (Sebastes, Anoplopoma), or firmly ankylosed to the latter 
(Scorpaena, Platycephalus), or form part of the external armature 
of the head (7'rigla, Dactylopterus). The structure of the base of 
the pectoral fin appears to afford important characters for the 
definition of the families, as first pointed out by Guill; these 
