OF THE SKULL IN LEPIDOSTEUS OSSEUS. 
459 
There is a squarish ear of cartilage on each side the pituitary body, growingfrom the 
trabeculae, and looking outwards and forwards ; these are the “basi-pterygoid processes” 
(i b.pg .), so familiar to us in the Amniota; to these the pedicles of the suspensorium 
(pd.) are articulated. Behind these the auditory capsules are seen as very large 
masses, completely confluent with the chondrocranium. Below (Plate 32, fig. 2, vb.), 
the vestibule forms an almost hemispherial projection; this is caused by the sacculus, 
which contains the otolith (fig. 3, ot.). 
Behind this there is a lesser eminence caused by the ampulla of the posterior canal 
(p.s.c.), between it and the larger cavity we see a shallow fossa. On the outside of 
this fossa the capsule projects, where it contains the horizontal canal (, h.s.c.), and under 
this projection there is an oblong articular cavity for the hyomandibular. 
Outside this, and between it and the superorbital band ( s.ob.c.), there is a rounded 
projection. This corresponds with the lateral pre-auditory mass seen in Teleostei and 
ossified as the so-called post-frontal—my sphenotic (“ On the Salmon’s Skull,” Phil. 
Trans., 1873, Plate 7, figs. 1-3). 
Above (Plate 32, figs. 1, 5, sp.o., a.s.c., h.s.c., p.s.c.), the outline of the large ear 
capsules is sinuous, the sinuosities being caused by the bulgings of the horizontal and 
posterior canals, and by the sphenotic process. Between the capsules, above, the 
tegmen cranii (s.o., t.cr.) is developed both over the occipital and the post-sphenoidal 
regions. This roof is rather pointed behind, over the foramen magnum, and has 
an evenly concave margin in front; there it forms the hinder boundary of the large 
fontanelle (fo.), which is a short oval, emarginate in its narrow fore end. In front 
of the fontanelle there is a considerable ethmoidal tegmen (t.cr.), which covers the 
olfactory lobes and the small hemispheres (Plate 32, figs. 4, 5, C la ., C 16 .) ; this is 
pointed behind in the middle, and laterally runs into the narrow arcuate superorbital 
band. The sides of the skull are oblique, the roof being more than thrice the width of 
the floor in the orbital region; these sides are mainly membranous; thus the orbito- 
sphenoidal cartilages are only represented by so much of the superorbital bands as 
belong to their territory ; the alisphenoidal cartilage is merely so much of the chondro¬ 
cranium as projects beyond the auditory capsule, laterally, between the basipterygoid 
and the sphenotic processes (b.pg., sp.o.). 
The small nasal capsules (fig. 5, ol.) have no separate cartilaginous roof; they are 
carried to the front of the snout. 
The suspensorium of the mandible has retained its primary continuity with the 
ethmo-palatine cartilage, so that it is still a palato-quadrate (Plate 32, fig. 2, p.pg 
pd.) ; but this is quite free now from the other primary connexion, namely, that with 
the trabecula (tr.). This large arch, with its pier, foregrowth, and free mandibular bar, 
has undergone a similar lengthening to that of the cranium. 
The pier or suspensorium is a large, oblongo-arcuate plate, ending in front in an oval 
sub-convex condyle, and a long, terete, pterygo-palatine process ; this latter is consider- 
