308 Mr. D. M. S. Watson on 



teeth, a thin i)late forming part of the side of the face, 

 a secondary palatal plate and a small ascending process 

 within the orbit (fig. 2). 



The alveolar part is supported internally by the vertical 

 plate of the palatine as far back as the transverse bone ; just 

 in front o£ this last bone its inner edge turns outwaiTls, has a 

 short contact with the transverse and an extensive one with 

 the palatal process of tlie jugal. The facial part of the bone 

 docs not enter into the rim of the orbit, but is connected by 

 sutures with the jugal, lachrymal, prsefront:d, and nasal. It 

 is pierced by two small foramina opening forwards and out- 

 wards; these apparently represent the pre-lachrymal foramen 

 of mammals. 



The inner edge of the alveolar part of the bone in its 

 anterior half sends inwards a secondary plate similar to, and 

 united with, the secondary plate of the palatine. 



The inner edge of the dorsal surface of the alveolar part 

 of the maxilla, just in front of and within the orbit, seems to 

 send up a small process to meet a corresponding process 

 from the pnefrontal ; it is, however, just possible that this 

 process really belongs to the palatine. 



Dentition (fig. 3). — The dentition is of the type of that of 

 Diademodon or Gomphognathus. All the teeth preserved 

 belong to the molar sei'ies, which is incomplete. On the 

 left side nine teeth are preserved, which I shall number 1-9, 

 the first being in front. 



I object to the division of the molar series t)f Gompho- 

 donts into premolars and molar, because ])remolar teeth in 

 mammals are, by definition, those which follow milk-teeth, 

 and probably belong to a later series than the permanent 

 teeth. There is no evidence whatever of tooth-change in 

 the molar teeth of Cynodonts. 



Teeth 1-3 are all of similar character ; their crowns are 

 oval, nearly as long as they are wide, very closely pressed 

 together and worn to a smooth gently convex surface. 



Tooth 4 is best preserved on tlie right side. It is broadly 

 oval, being 8 mm. across and nearly 5 long. The whole 

 centre of the crown of the tooth is worn down into a wide 

 longitudinally running groove, which is bounded both 

 externally and internally by a pair of somewhat broken 

 cusps. 



