333 
Geological Society of London. 
1. “ On the Rank and Affinities in the Reptilian Class of the 
Mosasauridce, Gervais.” By Prof. R. Owen. C.B., F.R.S., F.G.S. 
The autkor 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. Cope had recently 
thought he recognized in them Ophidian affinities, spoken of them as 
“ sea-serpents,” and formed of them an Order called Pythonomorpha. 
He then discussed in detail the various characters presented by the 
remains of these animals, and aiTived at the following conelusions : 
In the single occipital condyle and the composite structure of the 
mandible the Mosasaurians are Reptilian, as also in their proccelian 
vertebrae ; in the double oecipital hypapophyses, the bifurcate and 
perforate parietal, the presenee 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 
modifieation they are Iguanian, in another Monitorial, and their 
special group characters consist in the move 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 haemal arch with the centrum in certain of the caudal 
vertebras, 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 
Mosasauridae as a family of Lacertilia equivalent to the Iguanodon- 
tidje and Megalosauri dae in the Order Dinosauria. The order 
Lacertilia among Reptiles, being equivalent to the Order Carnivora 
or Fe ras among Mammals, the Mosasaurians wouldbe the equivalents 
of the Seals in the latter. 
2. “ Note on the Occurrence of the Remains of Hycenarctos in the 
Red Crag of Suffolk.” By Prof. Wm. Henry Flower, F.R.S., F.G.S. 
The traces of Hycenarctos described by the author in this paper 
consist of a right and a left first upper molar, which were obtained 
from the Red Crag of Waldringfield, and are so much alike, that 
but for the former being rather more wom they might have belonged 
tothe same animal. On comparison these teeth were found to show 
no appreciable difference from the coiTesponding teeth of the original 
specimen of Hycenarctos sivalensis 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 Hycenarctos, 
although certainly of later date, has been generally adopted. Re- 
mains of the genus have been found in the Pliocene marine sands 
of Montpellier {H. insignis, Gerv.), and in Miocene beds at Sansans 
(H. liemicyon), and at Alcoy, in Spain. A nearly perfect mandible 
of H. sivalensis has recently been obtained in its original locality by 
Mr. Theobald. 
