Annals of the Transvaal Museum. 
215 
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Op. 
Explanation of Plates. 
(Figures all of natural size.) 
Lower Jaw of Lystrosaurus. 
Outside view of the left ramus. Pal. Cat. No. 3099. 
Inside view of the left ramus. Pal. Cat. No. 3099. 
The symphysis seen from in front and below. Pal. Cat. No. 
3099. 
Endamaged hinder end of the outer portion of the angular. 
Pal. Cat. No. 3099. 
Outside view of an undamaged left hinder end of a jaw. 
Pal. Cat. No. 3098. 
Inside view of the same specimen. 
Back view of the same specimen. 
Section of the left ramus of a jaw behind the inner opening 
of the vacuity. Same specimen. 
Section of the left ramus of a jaw just in front of the hinder 
end of the dentary. Pal. Cat. No. 3099. 
Series of sections of a left ramus. Pal. Cat. No. 3097. 
Going backwards from left to right. The distances of 
every two sections are put between them. 
Section of an articulation part of a right ramus. Pal. Cat. 
No. 3096. 
Section of the same specimen a little further backwards. 
Section of the left angular across the connections of the two 
parts. Pal. Cat. No. 3095. 
Section of a jaw near the symphysis. Pal. Cat. No. 3095. 
Section of the left ramus of the jaw of the same specimen a 
little further backwards, showing the intricate suture of 
the angular and the opercular at this point. 
Section of a jaw showing the united opercularia. The angu- 
laria are still present. Pal. Cat. No. 3094. 
Section of the same specimen a little further forwards. 
= angular. 
= articular. 
= complementary. 
= dentary 
= Meckelian cavity. 
= opercular. 
Pa. = prearticular. 
Qa. = quadrate. 
Sa. = surangular. 
x. = a saw cut. 
i.o. = inner opening of the vacuity 
in the jaw. 
After the above was written and ready for the printer, I, for the 
last time, looked up the available literature and found a paper by 
Mr. IE M. S. Watson, “On some Revtilian Lower Jaws,” in the 
Ann. and Mag. of Nat. Hist. London, Ser. 8, Yol. 10, No. 60, Dec. 
1912, which for reasons outside my power had escaped my notice. 
To my great astonishment I saw that the description of the lower jaw 
of the Anoinodontin did not agree with my observations on the 
Lystrosaurus jaw. The most marked difference between the two 
descriptions is that Watson finds a separate coronoidal element between 
the dentary and the complementary, bone which the closest scrutiny 
of my Lystrosaurus jaws did not reveal. Further, Watson’s specimen 
did not show the inner opening of the vacuity in the jaw nor the canal 
in the symphysis. Also the arrangement of the bones around the much 
