33 
B.—Membrane bones which have become secondarily 
incorporated into the cranium :— 
1. Roof of Skull. Frontal (#/’r.—less the fused lateral 
line bone), Parietal (Par.). 
11. Mouth. Ossifications in the mucous membrane— 
Parasphenoid (Pa.S.), Vomer (Vo.). 
C.—Lateral line ossicles and bones formed by the 
modification of such:—Lachrymal (Lc.), Nasal (R.Va.), 
Preoperculum (P.Op.), Squamosal (see pterotic—Pt.0.), 
Suborbital chain, Supratemporal chain. 
D.—Bones formed either within or in immediate con- 
nection with the mandibular arch of the embryo :— 
Angular (An.), Articular (Ar.—less the fused lateral line 
ossicle), Dentary (D.—less the fused lateral line bone), 
Maxilla (Mz.), Mesopterygoid (Ms.Pt.), Metapterygoid 
(M.Pt.), Palatine (Pa.), Premaxilla (P.Mz.), Pterygoid 
(Pt.), Quadrate (Qu.). 
E.—Bones formed in connection with the hyoid arch 
of the embryo :— 
i. By modification of the upper segment of the arch 
itsel{—Hyomandibular (Hm.), Symplectic (Sy.). 
ii. By modification of the posterior branchiostegal 
rays of the arch—Interopereulum (J.Op.), Operculum 
(Op.), Suboperculum (S.Op.). 
¥.—Compound bones, 2.e., cranial bones to which 
ossiclés or bones originally developed in relation to the 
system of sensory canals have become secondarily fused to 
their superficial surface :—Articular (Ar.), Dentary (D.), 
Frontal (Fr.), Pterotic (Pt.0.), Sphenotic (Sp.0.). 
We shall now proceed to describe the visceral skele- 
ton proper, taking the hyoid arch first and the branchial 
arches afterwards. 
