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Show 1897.] DR. R. H. TRAQUAIR ON PAL.EOSPONDYLUS GUNNI. 313 but new collections were continually being obtained by the officers the Museum, w ho were periodically despatched on exploring expeditions. Among the more interesting acquisitions of 1896 were some crocodilian and ophidian skeletons from the red sandstones of the Territory of Neuquen, which were supposed to be of Cretaceous age, and had already yielded the Dinosaurian remains lately described by Mr. Lydekker. The Crocodiles (described by Mr. Woodward in the ' Anal. Mus. La Plata, Paleont. Argent.,' pt. iv. 1896) were of special interest as being of a Mesozoic type, with a short and broad head and a terminal narial opening. Their teeth wrere few and well differentiated into incisors, canines, and molars, apparently without any successional teeth. The Ophidian was in a wonderful state of preservation, but was still undescribed. The red sandstones in which these reptilian remains occurred were believed to be of the same age as the earliest deposits containing mammalian remains in Southern Argentina. Hence the latter were usually considered to date back to the Cretaceous period. The succession of the mammaliferous deposits of Patagonia and the adjoining territories had hitherto been most thoroughly investigated by Sehor Carlos Ameghino, who had conducted an exploring expedition each year since 1887, and had amassed an enormous private collection which his brother, Dr. Florentino Ameghino, had studied with results so important and so well known as not to need detailed recapitulation here. Above the red sandstones of Neuquen, and below the superficial pampean deposits, the brothers Ameghino now recognized two distinct mammalian faunas-the older of the Pyrotherium Formation, and the later of the Santa Cruz Formation, both particularly remarkable for the abundance of highly specialized Ungulata. Near the coast the marine Patagonian Formation fortunately separated these two freshwater or terrestrial horizons, and thus afforded a means of determining their age. The Cetacean remains found in the marine intercalation (as had been noted by Mr. Lydekker) seemed to correspond with those termed Miocene in the northern hemisphere; the Selachian teeth from the same formation presented by the brothers Ameghino to the British Museum were also of a Miocene or even early Pliocene facies. Mr. Woodward was therefore inclined to believe that the Santa Cruz fauna was not earlier than the Miocene, and might even be homotaxial with the Lower Pliocene of the northern hemisphere. There was no decisive evidence of any of the Patagonian mammals hitherto discovered dating back to the Cretaceous period. Dr. R. H . Traquair, F.R.S., exhibited and made remarks upon a new specimen of the supposed fossil Lamprey (Palceospondylus gunnl) from the Old Red Sandstone of Caithness, and read a note on its affinities (see below p. 314). Mr. E. T. Newton agreed with Dr. Traquair that the slight markings seen on the stone near the fish-remains, which had been PROC. ZOOL. Soc-1897, No. XXI. 21 |
