CARBONIFEROUS LABYRINTHODONT 563 
as its base behind it, but no trace of the attachment of any other 
tooth. 
The premaxillary and maxillary teeth on the right side by no 
means exactly correspond, either in position or in size, with those on 
the left. 
The tooth nearest the middle line in the right premawilla is six- 
tenths of an inch in diameter, and its base and its several fragments, 
when put together, show that it had a length of at least an inch and 
three-quarters. The two succeeding teeth are about half an inch in 
diameter at the base, and are not more than a quarter of an inch 
apart. Then follows an interspace of o’9 inch, in which I think I can 
trace the remains of the attachment of a great tusk. Then comes a 
large tooth, o'7 inch in diameter at the base; and then four small 
ones, none of which exceed 0°3 inch. The crowns of the succeeding 
teeth are all broken off, and lie with their points inwards upon the 
matrix, which covers this region and obscures their broken roots. 
None of them, however, have a basal diameter of more than 0°35 inch, 
and the last measures hardly more than o'2 inch at the base. The 
anterior of these teeth are about 1°3 inch in length, while the hinder 
ones become shorter, until the last was probably not more than halfan 
inch long when entire. The right vomer gives attachment to an immense 
tusk, o'8 inch in diameter at the base. It could hardly have been 
much less than three inches long, but it is unfortunately broken short 
off. The left vomer presents the surface for the attachment of a 
similar tusk, but the tooth itself is entirely detached. There is not the 
least trace of the existence of any other vomerine teeth besides these. 
On the left side, the palatine bone, eight-tenths of an inch behind 
the posterior nasal aperture, supports a tusk 06 inch wide at the base, 
which, when entire, was very nearly 2 inches long. The palatine bone 
is raised up into a ridge, so as to form a sort of alveolar wall on the 
outer side of this tusk, and the wall is continued backwards as a thin 
plate of bone directed almost horizontally inwards (/). Ata distance 
of three-quarters of an inch from the great anterior tusk, the alveolar 
plate, the margin of which is excavated in the interval, affords support 
to a tooth 0°35 inch in diameter at its base, and this is immediately 
followed by another of the same dimensions. These teeth are about 
o’9 inch long. 
On the right side, the base of a similar palatine tusk and part of an 
alveolar plate are visible ; but there are no small teeth, and the tusk is 
situated nearly an inch further back than on the left side. But the 
alveolar plate extends forward in front of this tusk, and presents a 
deep sinus, in which I suppose a tusk corresponding to that on the 
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