Annals of the Transvaal Mu s elm. 
133 
Also the longitudinal axis of most teeth is slightly inclined backwards. 
It could not be ascertained whether this double oblique condition is 
original. 
The second tooth from the front end of our fragment has a length of 
24,5 mm. measured along the middle of the flat side. The thirteenth tooth 
from the hinder end has still a length of 16,5 mm. while the last tooth on 
the dentary cannot have been longer than 7 or 8 mm. (only the lower 
half of this tooth is preserved). The mutual distance of the teeth is not 
the same. Mostly they stand so closely to each other that there is not 
sufficient room left for another tooth. This is the normal condition. 
Sometimes, however, they are further apart. This is the case with the 
three first teeth on our fragment. The space between these teeth has 
been partly cleared of matrix. In each space was found a small tooth, 
lying against the inner side of the high outer ridge of the dentary and not 
projecting above it. The base of these teeth is very thin and broke away 
during development ; it is situated much higher than the base of the 
large teeth. The length of the small teeth was about 12 mm. Their 
shape was not quite clear, but is probably the same as that of the new 
dentition on the palatine. 
The extreme end of each tooth is smooth. Below this the surface is 
covered with very fine ridges, running parallel with the tooth-axis. 
The lower two-thirds of the tooth-surface is covered with deep grooves 
also parallel to the tooth-axis. These grooves apparently indicate a 
labyrinthodont structure of the teeth. The pulp-cavity is filled with 
calcite. The upper end of this calcite cone is smooth, but further down- 
wards its surface is covered with grooves, parallel to its axis. These grooves 
owe their existence to the penetration of plications of the outer tooth- 
substance into the pulp-cavity. The labyrinthodont structure hereby 
becomes a certainty. 
The corresponding teeth on the maxillary are smaller than those on 
the dentary. There are 31 teeth projecting beyond the outer edge of the 
preserved part of the maxillary mentioned in the preliminary description. 
Their mutual distance is also irregular : they mostly stand closely against 
each other, but sometimes they are separated by a distance of more than 
the thickness of a tooth. The position of the preserved maxillary teeth 
is variable. Mostly the long axis of the oval-shaped section stands per- 
pendicular on the line of teeth but sometimes it makes an acute angle 
with the front end and sometimes with the hinder end of this line. The 
largest preserved maxillary tooth has a length of 14,7 mm. and the 
smallest of 5,1 mm. The structure of the maxillary teeth is the same as 
that of the dentary teeth. 
The row of teeth on the palatine is parallel to that on the maxillary. 
The twentieth tooth from behind has a length of 14,5 mm. ; the fifteenth, 
the tenth, the eighth, and the first from behind have respectively a length 
of 11 mm., 10,4 mm., 9,4 mm., and slightly more than 7 mm. This row 
of teeth starts at about 2,5 cm. from the hinder border of the palatine ; 
the ridge on which they stand starts somewhat earlier. The first tooth 
from behind corresponds in position with the ninth or tenth tooth from 
behind on the maxillary. Some small teeth of peculiar shape have been 
found on the inside of some of the palatine teeth. These teeth are not 
oval shaped as the ordinary palatine teeth or round as the small teeth on 
the pterygoid, but they are flattened and show a sharp edge in front and 
