732 
MR, T. W. BRIDGE ON THE OSTEOLOGY OF POLYODON FOLIUM. 
or.p. Orbitar process. 
op. Operculum. 
pg. p. Pterygoid process. 
p.br. Pharyngo-brau cbial. 
pt.r. Pterotic ridge. 
p.f. Parietal foramen. 
pt. Pterotic. 
pa.s. Parasphenoid. 
pr, py\ Rostral homologues of the parasphenoid. 
Q. Quadrate cartilage. 
sp.r. Sphenotic ridge. 
sy.l. Symplectic ligaments. 
Vo. Vomer. 
V 2 and V s . Rostral homologues of the vomers. 
Nerves. 
II. Optic. 
m.o. Motores oculi. 
tv. Trochlea ris. 
V, V". Foramina for exit of branches of trigeminus. 
VIP, VIP. Anterior and posterior openings of facial canal. 
IX. Glossopharyngeal. 
Vg. Vagus. 
PLATE 55. 
Fig. 1. Dorsal aspect of the skull. Reduced one-half'. 
Fig. 2. Ventral view. Reduced one-half. 
liy.g. Articular groove for head of hyomandibular. 
x. Prolongation of first visceral cleft. 
h. c. Haemal canal. 
Fig. 3. Side view of the cranium. Natural size. 
a.n. Anterior nares. 
p.n. Posterior narial opening. 
of. Orbital floor. 
i. h. Inter-haemal cartilages. 
i.n. Inter-neural cartilages. 
a.r. Anterior root of spinal nerve. 
p.r. Posterior root. 
z. Foramen in side wall of rostrum, 
