ESPECIALLY MYCTOPHOIDS 115 
basioccipital contacts the prootic bridge above the myodome. The antero-dorsal 
extent of the bone provides a partial separation of the two otolith chambers. The 
otolith chambers themselves extend anteriorly to end in a recess in the prootic just 
posterior to the internal opening of the facial foramen. 
The prootics divide to produce an internal lamina which meets its partner in the 
mid-line forming the prootic bridge, and an outer lamina which curves laterally in 
the dorsal region and provides part of the wall of the cranial cavity. Posterior to the 
prootic bridge the otolith chambers communicate with the cranial cavity through a 
large oval fenestra. On the orbital face, the prootic meets the sphenotic and 
pleurosphenoid dorsally. The prootic contains the trigemino-facialis chamber 
which is divided by bone into a medial pars ganglionaris and a lateral pars jugularis. 
The pars jugularis is a very short horizontal canal on the lateral face of the prootic 
which opens anteriorly in the hind wall of the orbit. There is a single foramen lead- 
ing from the pars ganglionaris into the pars jugularis, the facial foramen, which 
transmitted the hyomandibular trunk of the facial nerve. The palatine branch of 
the facial nerve passed through a foramen medial to the facial foramen down into the 
myodome. The hyomandibular nerve passed out through the posterior opening of 
the pars jugularis, which also transmitted the jugular vein and the orbital artery. 
The artery and vein were the only structures which passed through the anterior 
opening of the pars jugularis. The trigeminal and remaining components of the 
facial nerve passed through two foramina-in the orbital face of the prootic, dorso- 
medial to the anterior opening of the pars jugularis. The larger of the two foramina 
is the trigeminal foramen and presumably transmitted all of the remaining branches 
except the superficial ophthalmics. These latter components passed out through a 
small foramen dorso-medial to the trigeminal foramen. 
s.0.V, VIl 
f.f 
10mm p.t.f.c pie 
Fic. 51. Eurypholis pulchellus (Woodward). Neurocranium in lateral view. The 
inset shows the prootic in antero-lateral view. From B.M.N.H. number P.10984. 
