714 TRANSACTIONS OF SECTION C. 



8. On Distinctions in Dentition between the Fossil Reptilia classed as 

 Cynodontia and Gomphodontia. By Professor H. G. Seeley, F.B.S. 



These two divisions of the Theriodont reptilia appear to be more definitely 

 distinguished by dental conditions than was evident when they were defined in 

 1895. The Gomphodontia are those animals which resemble mammals in the 

 unworn and worn conditions of the grinder teeth and in the diastema which 

 exists between the canine and the first molar. The author found thirteen molar 

 teeth in the mandible of Gomphognathus Kannemeyeri which are similar to each 

 other. In G. Polyphagus only nine molar teeth were found, but indications exist 

 of at least four minute pointed conical teeth in advance of the molars, all of which 

 appear to have the crowns broken, and their removal lengthens the diastema. 

 The fragment of a mandible figured in illustration of Tritylodon has similar teeth 

 in the diastema apparently worn level with the jaw during the life of the animal, 

 and now distinguished under the specific name dimorphodon. These species are 

 separated from Gomphognatlms as Diastemodon. The teeth in the diastema are 

 regarded as milk molars, which are never shed, but cease to be eflective by losing 

 their crowns. 



There is no evidence that any Gomphodont reptile has teeth upon the palate, 

 on the maxillary, palatine, pterygoid, or other bone, and in this condition they 

 resemble mammals. 



The Cynodontia, in ^lurosaurus, a carnivorous type with small, sharp, conical 

 molar teeth, are already known to have teeth upon the palate ; but the specimens have 

 had the mandible closed upon the skull, so that the structure of the palate is not 

 seen. The author has received two specimens from Dr. Kanuemeyer which give 

 u better knowledge of the palate iu the genus Oyuognathus. In one specimen the 

 palatal plate of the maxillary bone carries on its inner third a strong wedge of 

 dental armature. The individual teeth form several parallel rows blended together 

 in the manner of Hyperodapedon. This dental mass is blended with the maxillary 

 bone except in front, where one plate is lost from an empty socket. The ciowns 

 are but slightly elevated, of ovate form carrying one or two elevated lines, and 

 sometimes a few granules. 



The second specimen is crushed, and the species is not jet determined. It 

 shows that the maxillary armature of crushing-plates met in the medial line of the 

 palate. It also shows that an armature of crushing-teeth forming a flat wrinkled 

 enamelled surface was developed upon the edge of the palatine bone, so as nearly to 

 surround the posterior nares. This structure is entirely behind the maxillary 

 plate instead of being parallel to it, as in Hyperodapedon. The maxillary plate 

 has now been partly uncovered in the type 'Gy7iognathus crateronotus, and shows 

 that the palate carries teeth like those in the new specimens. The alveolar teeth 

 are so typically carnivorous that these palatal teeth are unexpected structures. 



Report on the Fossiliferous Drift Deposits at Kirmington, 

 Lincolnshire, <i:c. — See Eeports, p. 296. 



10. Interim Report on the Correlation and Age of South African 



Strata, &c. 



1 1 . Report on Topographical and Geological Terms used locally in South 



Africa.- — See Beports, p. 286. 



12. Report on the Exact Significance of local Terms, 



