﻿Geological Society of London. 333 



1. " On the Eank and Affinities in the Eeptilian Class of the 

 Mosasauridce, Gervais." By Prof. E. Owen, C.B., F.E.S., F.G.S. 



The author stated that while the Mosasaurians had been originally 

 referred to the Cetacea by Camper, then to Crocodilia by Faujas de 

 St. Fond, and to the Lacertilia by Cuvier, Prof. Coj)e had recently 

 thought he recognized in them Ophidian affinities, spoken of them as 

 " sea-serj)ents," and formed of them an order called Pythonomorpha. 

 He then discussed in detail the various characters presented by the 

 remains of these animals, and arrived at the following conclusions : 

 In the single occipital condyle and the composite structure of the 

 mandible the Mosasaurians are Eeptilian, as also in their procoelian 

 vertebrae ; in the double occipital hypapophyses, the bifurcate and 

 perforate parietal, the presence of the "columella," the composite 

 formation of the suspensory joint of the tympanic and in the type of 

 the tympanic, the frame of the parial nostrils and the structure and 

 attachment of the teeth, they are Lacertian. In one special dental 

 modification they are Iguanian, in another Monitorial, and their 

 special group chai'acters consist in the more extensive fixation of the 

 pterygoids and ossification of the roof of the mouth, the large pro- 

 portion of the vertebral column devoid of zygapophyses, the con- 

 fluence of the hasmal ai'ch with the centrum in certain of the caudal 

 vertebrae, and the natatory character of the fore and hind limbs. 

 These distinctive characters did not appear to the author to be 

 sufficient for ordinal rank, and with P. Gervais he regarded the 

 Mosasaurida? as a family of Lacertilia equivalent to the Iguanodon- 

 tidee and Megalosauridee in the order Dinosauria. The order 

 Lacertilia among Eeptiles, being equivalent to the order Carnivora 

 or Feras among Mammals, the Mosasaurians would be the equivalents 

 of the Seals in the latter. 



■ 2, " Note on the Occurrence of the Eemains of Symiarctos in the- 

 Eed Crag of Suffolk." By Prof. Wm. Henry Flower, F.E.S., F.G.S. 



The traces of Symnarctos described by the author in this paper 

 consist of a right and a left first upper molar, which were obtained 

 from the Eed Crag of Waldringfield, and are so much alike, that 

 but for the former being rather more worn they might have belonged 

 to the same animal. On comparison these teeth were found to show 

 no appreciable difference from the corresponding teeth of the original 

 specimen of SycBnarctos sivcdensis from the Sewalik Hills, and 

 hence the author did not venture to regard them as representing a 

 species distinct from the Indian one. The author discussed the 

 synonymy of this species, which was first described by Falconer and 

 Cautley, in 1836, under the name of Ursus sivalensis. The genus 

 Agriotherium was established for it by Wagner in 1837, and the 

 names Amphiarctos and Sivalarctos were given to the genus by 

 Blainville in 1841 ; but Falconer and Cautley's name Hyainarctos, 

 although certainly of later date, has been generally adopted. Ee- 

 mains of the genus have been found in the Pliocene marine sands 

 of Montpellier {S. insignis, Gerv.), and in Miocene beds at Sansans 

 {E. liemicyon), and at Alcoy, in Spain. A nearly perfect mandible 

 of H. sivalensis has recently been obtained in its original locality by 

 Mr. Theobald. 



