336 Annals of the South African Museum. 



that the Trirachodon molar is related to that of the Stormberg fossil 

 in much the same way that the molar of the pig is related to that 

 of the opossum, but it seems impossible that the two animals can 

 be more nearly related than an ungulate and a marsupial. 



If this new form is a mammal it must be regarded as the repre- 

 sentative of a new order, and if, as I believe, it ought to be regarded 

 as a Cynodont, it will have to be the representative of at least a new 

 family. 



The exact horizon of the fossil is unknown. Professor Schwarz 

 writes me that Paballon might mean any horizon from Molteno 

 Bed to the Cave Sandstone, but from the matrix of the fossil it 

 seems highly probable that it comes from the Eed Beds. In any 

 case it may be regarded as certain that the fossil is of Lower 

 Jurassic age. This is interesting from the fact that no Cynodont 

 has hitherto been got from beds younger than the Burghersdorp 

 or Upper Triassic. 



I suggest for this interesting fossil the name Tritheledon riconoi, 

 g. et sp. nov., and the new family of which it is the type may be 

 called the Tritheledontida. 



PLATE XXII. 



FIG. 



30. Side view of fragment of the skull of Tritheledon riconoi. x 2 



31. Palatal view of fragment of skull of Tritheledon riconoi. x 2 



32. Front view of ditto, x 2. 



33. Restoration of front of skull of Tritlteledon riconoi. Nat. size 



34. Anterior view of molar tooth of Tritheledon riconoi. x 6. 



35. Palatal view of molar tooth of Tritheledon riconoi. x 6. 



36. Posterior view of posterior molar of Tritheledon riconoi. x G. 



