Geological Society of London. 331 



2000 feet below the true Wenlock series, and about tbe horizon of 

 the Upper Llandovery rocks. 



2. "Notes on a Mammalian Jaw from the Purbeck Beds at Swanage, 

 Dorset." By Edgar Willett, Esq., communicated by the President. 



Excavations were undertaken last summer in this locality (Durl- 

 stone Bay, Swanage), where, rather more than twenty years since, 

 the jaws of sixteen new species of Mesozoic mammalia were found 

 by Mr. Beccles. These, though less successful than the former, 

 resulted in the discovery of the larger part of the right mandibular 

 ramus of a marsupial, about 1^ 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 Triconodon, described by 

 Prof. Owen in his monograph (Palseont. 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. Triacantho- 

 don, 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 mordax, than to attribute it to a new species of the genus. 



III.— June 8, 1881.— E. Etheridge, Esq., F.R.S., President, in the 

 Chair. — The following communications were read : — 



1. "The Eeptile-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.S. ; wfth a Note on the Geological 

 Horizon of the Fossils, by 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 re-examination of the whole collection neces- 

 sary. All the species hitherto discovejred 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 con- 

 sidered 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 



