448 
MR. W. K. PARKER ON THE DEVELOPMENT 
Under tlie skull there is a long beam of bone, reaching to the middle of the vomers, 
lying there somewhat above them, and then escaping, showing a free keel; this is the 
“ parasphenoid." It runs backwards, gently broadening, and then narrowing again, 
and gradually losing its keel, up to the “ basipterygoid processes/' it flanks them 
with a small pair of wings, and is then alate again, more extensively, under the “ sac- 
culus ” of the ear, and ends as two flat processes under the basioccipital, and nearly 
reaching to its end. 
B. On the endo-crcmial bones. 
In the hind skull I fail to find a distinct supraoccipital under the roof, for the 
exoccipitals meet there, and are separated only by a narrow tract of cartilage. The 
basioccipital is large, and projects beyond the arch ; its hollow articular face is 
transverse, and notched above and below. The exoccipitals are large, and finish the 
arch above. The auditory capsule is invested by four cartilage bones on each side, 
viz.: a large prootic, a middle sized epiotic, and a small opisthotic, and the sphenotic 
bone which is of the average size, and ossifies the post-orbital angle of the endocranium, 
where the fore part of the auditory capsules are imbedded. I can find no “ pterotic ” 
under the squamosal. There are two alisphenoids, and they ossify the basipterygoid 
processes, but I find no distinct basisphenoid, presphenoid, nor orbito-sphenoids; 
although after the brain cavity has retreated, losing much of its front part, a bony 
plate is found in the presphenoidal region. This plate is thin, fenestrate, and rests 
upon the parasphenoid. I believe that it is formed by the coalescence of the once 
distinct lateral ethmoids, which were at first formed in the sides of the fore part of the 
chondrocranium, like the primary elements of the Frog's “ girdle-bone ” (see Plate 38, 
figs. 2, 3, l.eth.). The rostral part of the endocranium is, I believe, unossified, even 
in the adult. 
The quadrate and metapterygoid bones occupy only part of the mandibular suspen- 
sorium; the rest remains unossified; the metapterygoid bone takes up the part which 
answers to the pedicle and rudimentary otic process ; a facet of cartilage covers it 
where it articulates with the “basipterygoid process." The hyomandibular is fenestrate 
and well ossified; it is only half as large as the mandibular suspensorium. A short 
tract of cartilage separates its upper from the slender long symplectic. 
The articulare is a strong solid mass of bone, capped by a saddle-shaped condyle 
for articulation with the quadrate. 
The small inter-hyal piece is not ossified, but the epi-, cerato-, and hypo-hyals are ; 
the long double basi-hyal (“ ento-glossal") does not become solid bone, but it is 
endosteally hardened. The fore part of the basi-branchial series is slightly ossified, the 
arches are as well ossified as in the ordinary Teleostei; thus there are in the first four 
arches a pharyngo, epi-, cerato-, and hypo-branchial piece, largely converted into bone ; 
the fifth is ossified, but it only has the cerato-branchial element in it. 
