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Show 206 MR. E. T. NEWTON ON SOME [Apr- 2, ornamentation is peculiar and exactly corresponds with that found on the pectoral plate originally described by Dixon. The tubercles on all these specimens are sharp, conical, and more or less connected together by ridges which give a reticulated appearance to the plates when closely examined. Spines which cannot be distinguished from those of A. egertoni are found at Barton ; but the skull above described differs from A. egertoni in several particulars, although it is only the supraoccipital bone which is available for comparison. This bone, so far as it is preserved, has a different form from that of A. egertoni, being proportionally wider and with less deeply grooved mucus-canals. The ornamentation of the bones, likewise, is of another character ; the tubercles are more numerous, more rounded, and with little or no indication of the reticular structure between them ; moveover, they have a greater tendency to run together in radiating lines, and to become less distinct towards the margins of the bones. It will be obvious that this skull cannot be referred to A. egertoni, and there seems no good grounds for referring it to A. ? bartonensis, which is a smaller form and not certainly belonging to the genus Arius. On the other hand, there can be no question as to the otolith found in this skull being specifically identical with the one figured and described by Herr E. Koken (6) as Otolilhus (incertce sedis) crassus, and this specific name must therefore be adopted for our specimen, which will henceforth be known as Arius crassus. Should the spines called A. bartonensis prove eventually to belong to the same species, the name of A. crassus having priority will have to be retained, although it may be a less appropriate cognomen. According to Herr Koken this form of otolith has been found at Headon Hill, Isle of Wight, and also in Oligocene strata at Lattorf, Cassel, Westeregeln, and Waldbbckelheim, in Germany. The specimen from the Miocene of Tortonese, referred to by Herr Koken as possibly belonging to this species, which is figured by Dr. Sismonda (Mem. Accad. Sci. Torino, 1849, ser. 2, vol. x. pi. 2. fig. 71), does not seem to m e to belong to the genus Anus. lt is quite likely that one or other of the three forms of otoliths from Barton may belong to A. egertoni or A. bartonensis ; but it is likely to be Ions before the means of correlating them will be found, and I have thought it best to distinguish them provisionally as Arius (otolithus) sp. A (fig. 4), Arius (otolithus) sp. B (fig. 5), and Arius (otolithus) sp. C (fig. 6). Should the otolith from Ankoala, Madagascar (fig. 7), prove to belong to an undescribed species, I would suggest that it be named after the gentleman who brought it to this country, Arius baroni. Works that may be consulted on Fossil Siluroid Fishes. 1. C O P E , E. D.-The Vertebrata of the Tertiary Formations of the West. Rep. U.S. Geol. Surv. vol. iii. Book i. p. 62 (1884). 2. D I X O N , F.-Geology and Fossils of Sussex. 1st edit. 1850, p. 204; 2nd edit. 1878, p. 244. 3. G U N T H E R , A . - " Contributions to our Knowledge of the Fish |