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MR, W. K. PARKER OK THE DEVELOPMENT 
These next bones are the “ ethmo-nasals,” or superficial splints of the ethmoidal 
region; they are close together along the mid line, sharp and narrow between the 
fore part of the frontals, and then wider ; they reach, behind, within an inch and a-half 
of the orbits, and then run forward up to the nasals (proper). These latter are small, 
short, widely-crescentic plates, that lie on the small, distal, olfactory sacs ; they are the 
ossa terminalia of the upper mucous series. The nasals finish the skull-beak above; 
below, an oblique transverse plate of bone supports the prenasal pad or remnant of the 
larval sucking-disk; it may be called the “ prenasal bone/’ The nasal bone sends a 
process obliquely across the nasal opening ; this bone lies in the membranous bar, which 
was developed early, dividing the “ nostril” into two holes. Behind and under the 
prenasal and nasal bones we have the two short thick premaxillaries, which carry some 
very large, sharp teeth, as well as a rasp of smaller denticles. These bones have a 
palatal as well as a dentary region; and between the two the bone is punched with 
holes by the foremost teeth of the mandible, as in the Crocodile; the palatine processes 
diverge a little, behind, to embrace the vomers. 
The vomers are very long, thin styles of bone, closely co-adapted along the mid line 
of the palatal region of the rostrum up to its hinder fourth ; they have their lower 
face covered with a rasp of very small teeth. 
Outside these there is on each side a larger splint, which reaches from the pre¬ 
maxillary to the antorbital space. The outside of each bone is bevelled and helps to 
carry the large sub-marginal teeth ; these are the superficial palatines. Outside these, 
on the margin, we have the “ maxillary chain ” of mucous bones, about fifteen on each 
side, but some of them are ankylosed together ; they increase in length from before 
backwards. The preorbital (prequadrate) space is overlapped by the last two of this 
chain; these are free ; the larger front bone answers to the free part of the “ os mysta- 
ceum ” of an Acanthopterous Teleostean ; the lesser scale to its jugal. A large splint 
passes along by its sharp fore end, on the inside of the parosteal palatine, nearly 
to its middle ; it broadens rapidly at the prequadrate space and turns downwards, 
as a rounded wing. It is notched below close in front of the quadrate condyle, and 
then passes backwards as a large lanceolate splint, which is closely applied to nearly 
all the inner face of the mandibular suspensorium ; this is the pterygoid bone, the 
osseous counterpart of the whole palato-quadrate arcade. Above the broad hind part 
of that arcade, close in front of the basi-pterygoid articulation, there is a much smaller 
lanceolate splint, the meso-pterygoid ; it lies inside, but rises somewhat above the 
obliquely directed suspensorium. An oblong splint, rather larger than the last, lies on 
the outside of the lower face of the suspensorium, and is dilated where it fits to the 
enlargement at the quadrate condyle ; this is the “ preopercular”: a very different bone 
from its counterpart in the Teleostei, and like the lower part of a Frog’s squamosal. 
These four—the superficial palatine, the pterygoid, the mesopterygoid, and the pre¬ 
opercular—are the splints of the palato-quadrate arcade ; the rest of the mandibular 
splints are on the free ramus, and will be described soon. There is a perfect “ ci rerun- 
