566 
ME. W. K. PAEKEE ON THE STEITCTUEE AND DEVELOPMENT 
is quite similar to what are seen in the long-faced Monitor, whose vomers are long, and 
only moderately broad, planks. 
W e saw that in the branchial stage the teeth were distributed in two concentric semi- 
circular rows. Those of the premaxillary had the vomerine rows within and behind 
them, and the maxillary series were similarly imitated by those of the bony palatine 
(Plate 24. fig. 5). Now all is changed (fig. 6); for not only are the vomerine rasps 
turned the other way, but the little palatine, with its row, has its gently convex edge 
looking forwards, and vice versd, the opposite to the row on the vomer, and nearly at 
right angles to the maxillary series ; this type is a “ lechriodont.” 
This little bone, which has turned outwards, like a railway signal, is steep ; it helps 
to surround the inner nostril, and ties the vomer to the maxillary. 
This is not a rare condition for the palatine bone of a Urodele ; it occurs also in the 
Batrachia ; for instance, in Ceratophrys, where it is attached to the under surface of the 
ethmo-palatine ectostosis. 
But as a simple bony plate it may be compared with the palatine of the Monitor 
Lizard, which has but little longitudinal extent, and, growing directly outwards, 
forms a second or anterior “ os transversum,” tying the vomer to the maxillary, as in 
Amblystoma. That process of the pterygoid bone which fastens on to the palatine 
(nearly reaching the vomer), in the Monitor, is absent in Amblystoma ; but the apex of 
its pterygoid runs outwards towards the jugal exactly as in that Lizard. Thus the 
palatine and pterygoid plates, which were in the larval state one bone, are now far 
apart, and their axes, which were coincident, are now at a right angle with each other. 
Moreover, in the fourth stage, the pterygoid was seen to have arisen as a mere pro- 
cess of the palatine ; it is now twenty times the size of the old stock from which it 
detached itself. 
The pterygoid is, like the palatine (or “ ethmo-palatine ”), composed of a cartilage 
and a bone; for the palatine dentigerous plate is the bony counterpart (or companion) 
of the antorbital cartilage ; and the pterygoid bone, by using up the substance of the 
“ chondropterygoid,” has enucleated, as it were, a distinct epipterygoid cartilage 
(Plate 27. fig. 7, e.pg.) *. 
The pterygoid (Plate 24. fig. 6, pg .) now binds more completely under the pedicle, 
which it hides, and the quadrate, or lower part of the suspensorium. The quadrate 
bony centre has ossified the greater part of the suspensorium, and even the narrowed 
ascending process is bony (Plate 27. fig. 7). 
* This unossified rod is partly the fixed postpalatine cartilage of a former stage, and partly the anterior end 
of the tongue of cartilage which grew from the front of the suspensorium. 
In the Chelonians and Lizards a similar rod becomes enucleated from the indifferent tissue covering the hony 
pterygoid ; this becomes semicartilaginous, and is then invested with a hony sheath. It keeps its half-prostrate 
posture in the Chelonia, but in Lizards uplifts itself, gradually, to an almost erect position ; this “ columella ” 
has its base, then, resting on the bony pterygoid, and its capital leaning against the anterior part of the prootic 
above {Monitor), or reaching, by its upper epiphysis, to the lower edge of the parietal ( Lcemanctus ). 
