132 
Annals oe the Teansvaal Museum, 
While developing skull No. 1 some remains of the hyo-branchial 
skeleton were found. These consist of a large row of small bones, which 
are nearly in a straight line and another smaller row of bones which 
form a bent line. The straight row consists of ten elements ; in the bent 
row there are four. If the ten elements of the straight row are numbered 
from one end, we get Nos. 1-4 in a continuous line ; No. 5 lies parallel 
against No. 3 ; No. 6 lies parallel against No. 4 ; Nos. 5-10 also form a 
continuous line, parallel to that of Nos. 1-4. Nos. 1 and 2 are of about 
equal size and larger than the others ; these are also of about equal size. 
The two first elements bear a series of tooth-like processes on one edge. 
These teeth are very long, slender, sharp-pointed cones. As they have 
been noticed on some of the other elements it is probable that they 
occurred on all. I must mention here that most of the elements are 
broken and some of them are only represented by their impression on the 
matrix. Also, in the course of development, other elements of the same 
kind have been met in isolated positions in the matrix, and owing to their 
very delicate nature, were unfortunately destroyed. The length of 
elements 1 and 2 was about 17 mm., their height about 4 mm. and their 
thickness may have been 2 mm. 
The other elements have a length of 13 mm. and less. The length of 
the teeth is less than 3 mm. 
It is impossible to say which arches are represented. It is not im- 
probable, however, that there are both hyoidean and branchial arches. 
In the first place there seem to be three distinct series of elements, which 
could be taken as the remains of three arches. Secondly, the number of 
elements is sufficient for three arches. Whether these branchial arches 
bore gills only during the earlier lifetime of Myriodon is a question which 
cannot be answered from the present material. 
The Teeth (PL XVIII). There is a row of large teeth on each 
maxillary, palatine and dentary. These teeth diminish in height back- 
wards. Further, the palatal surface of the pterygoids and partly also of 
the basisphenoid is covered with multitudes of small teeth. Similar small 
teeth occur near the junction of the palatine with the prevomer and are 
probably situated on the latter. The upper and inner surface of the com- 
plementary also bears small teeth. Somewhere near the junction of the 
palatine and the prevomer there is a large tooth, visible .on either side. 
On the right the tooth itself is still preserved, on the left there is only an 
impression in the matrix. The exact position of this tooth is not clear, 
but it seems that it is situated at the front end of the row of teeth on the 
palatine and directly behind the hinder end of the choana. In front and 
to the inside of this large tooth there are some smaller ones, which have 
about the size of the lesser ones on the palatines. The rows of teeth on 
the maxillary, palatine, and dentary are pleurodont. 
The teeth on the dentary are best displayed on the fragmentary right 
ramus of the mandible already mentioned above (PI. XIX, fig 1). Parts 
of the mandible and of the maxillaries of skull No. 1 have been preserved, 
but the rows of teeth are in a very poor condition. On the portion of the 
right ramus of the mandible there are 29 large teeth, which project beyond 
the outer edge of the dentary. These teeth are sharp-pointed and 
conical and direct their top inwards and backwards. A transverse section 
has the shape of a laterally compressed oval. The long axis of this oval 
makes an acute angle with the hinder end of the dentary in most teeth. 
