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. ‘he tubercles 
on all these specimens are sharp, conical, and more or less connected 
together by ridges which give a reticulated appearance to the plates 
wher closely examined. Spines which cannot be distinguished from 
those of A. egertoni are found at Barton ; but the skull above de- 
scribed 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, hasa 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 belong- 
ing 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 Ovolithus 
(tncerte sedis) crassus, and this specific name must therefore be 
adopted for our specimen, which will benceforth be known as Arius 
erassus. Should the spines called A. bartonensis prove eventually 
to belong to the same species, the name of 4. crassus having priority 
will have to be retained, although it may be a less appropriate cog- 
nomen. 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 Waldbéckelheim, 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. pl. 2. 
fig. 71), does not seem to me to belong to the genus Arius. 
It is quite likely that one or other of the three forms of otoliths 
from Barton may belong to d. egertoni or A. bartonensis ; but it 
is likely to be long 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. Corr, E. D.—The Vertebrata of the Tertiary Formations of the 
West. Rep. U.S. Geol. Surv. vol. iii. Book i. p. 62 (1884). 
2. Dixon, F.—Geology and Fossils of Sussex. 1st edit. 1850, 
p- 204; 2nd edit. 1878, p. 244. 
3. GUnTHER, A.— Contributions to our Knowledge of the Fish 
