On a Nciu LahyrinUiodont Rhinesuchus Wliaitsi. 375 



columella auris. The upper end is in the auditory notch, proving 

 that the tympanic membrane must have been superficial as in the 

 frog and stretched across the notch or foramen. The columella 

 auris is preserved in position on both sides of the specimen. 



The back part of the parasphenoid (vomer) covers part of the 

 basioccipital and articulates at the sides with the exoccipitals. The 

 anterior part of the parasphenoid must have been long and slender. 

 Only the base of it is preserved, but this measures only about 

 18 mm., whereas immediately behind this the bone broadens out 

 to 45 mm., and at its broadest part to 58 mm. The most remark- 

 able feature of the parasphenoid is that a large part of it is covered 

 with minute teeth. From the lateral edges where it articulates with 

 the pterygoids the dentigerous areas pass inwards and forwards 

 to the base of the narrow anterior portion. The narrowest part 

 of the tooth-bearing region is 13 mm. wide. Thei'e are no teeth 

 behind this region. In the type specimen only the posterior and 

 inner parts of the pterygoids are preserved, and these, like the 

 parasphenoid, bear innumerable small teeth, which are not all 

 over the bone but along a band near the middle. The widest part 

 of this dentigerous band is about 30 mm., the narrowest so far as 

 preserved about 15 mm. In the Zeekoegat specimen a considerable 

 part of the front of the bone is preserved, and the small teeth are 

 seen to be continued far forward. 



Passing up from back of each pterygoid are two bones which firmly 

 support it. The more anterior passes upwards and inwards, and 

 seems to correspond to the columella cranii of reptiles. It is 

 attached to the parietal by the side of the pineal foramen. The 

 other lies behind the outer part of the supposed columella cranii, 

 and forms the anterior wall of the large tympanic cavity. It is 

 probably the prootic. 



Fragments of the maxilla show that it had a large series of small 

 flattened labyrinthodont teeth, and inside the maxilla lay the pala- 

 tine with a large number of small teeth irregularly arranged, but 

 roughly in three or four rows. The palatine teeth are considerably 

 larger than those on the pterygoids and parasphenoid, but they are 

 only about one-third the size of those on the maxilla. One fragment 

 of the snout shows a large rounded labyrinthodont tooth. It is to 

 the inner side of the row of palatine teeth, and is evidently borne by 

 the prevomer. 



Though in a fragmentary condition, most of the mandible is pre- 

 served. The jaw has along its upper and outer border a large series 

 of small flattened labyrinthodont teeth, very similar to the row on 



