154 Geological Society. 
the jaws of sixteen new species of Mesozoic Mammalia were found 
by Mr. Beckles. These, though less successful than the former, 
resulted in the discovery of the larger part of the right mandibular 
ramus of a marsupial, about 13 inch long. Six teeth are preserved 
in situ. This specimen was described and its affinities discussed by 
the author. He referred it to the genus Z’riconodon, described by 
Prof. Owen in his monograph (Paleont. Soc. 1871). The peculiarity 
of this specimen is that it has four teeth having the form of true 
molars, while those previously found have only three. Triacan- 
thodon, indeed, has four true molars ; but between it and the specimen 
described there are some important differences of detail. The dental 
peculiarity may be explicable on either of two hypotheses suggested 
to the author by Prof. Flower; and he thinks it better to refer it to 
Triconodon mordaw than to attribute it to a new species of the 
genus. 
June 8, 1881.—Robert Etheridge, Esq., F.R.S., 
President, in the Chair. 
The following communication was read :— 
“The Reptile Fauna of the Gosau Formation, preserved in the 
Geological Museum of the University of Vienna.” By Prof. H. G. 
Seeley, F.R.S., F.L.S., F.G.8.; with a Note on the Geological 
Horizon of the Fossils, by Dr. Edward Suess, F.M.G.S. 
The collection of Reptiles described in this paper was obtained at 
Neue Welt, near Wiener Neustadt, by tunnelling into the freshwater 
deposits which there yield coal. A part of the collection was 
described by Dr. Bunzel in 1871; but the author’s interpretation of 
the fossils rendered a reexamination of the whole collection neces- 
sary. All the species hitherto discovered are new, and, with the 
exception of those referred to Crocodilus, Megalosaurus, Ornithochi- 
rus, and Emys, are placed in new genera. Nearly all the bones are 
more or less imperfect. 
The Iguanodon Suessii, of Bunzel, was referred to a new genus, 
Mochlodon, characterized by the straight anterior end of the ramus 
of the lower jaw, and by the vertical bar in the middle of the teeth 
of the lower jaw. ‘There appear to be two teeth in the ramus. The 
tooth referred to the upper jaw has several uniform parallel vertical 
bars. A small parietal bone, referred by Bunzel to a Lizard, is 
considered by the author to belong probably to the same species ; 
and, with some doubt, he associated with it the articular end of a 
small scapula. 
Bunzel's Struthiosaurus austriacus was redescribed by the author, 
who indicated that the bones of the base of the brain-case, regarded 
by Bunzel as the quadrate bones, really belong to the occipital 
region, which necessitates a different interpretation. The foramina 
along the base of the skull were also described as presenting one of 
the characteristics of the Dinosaurian order. The base of the skull 
of Acanthopholis horridus was described, to show its relation to the 
