10 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
therium is only one among many other striking instances of the palaeontological 
acnmen of the talented authors of that work. At a later period, some other teeth of 
a rhinoceros from the same beds in the collection of the Asiatic Society of Bengal, 1 
were catalogued by Dr. Ealconer under the heading Rhinoceros , without the affix 
of any specific name. Dr. Murchison, however, in the ‘‘Palaeontological Memoirs” 2 
quotes these specimens as Rhinoceros perimensis, apparently on no better grounds 
than the locality from whence they came. Some (and perhaps all) .of the specimens 
do, however, certainly belong to that species. 
At a still later period, some detached teeth of a rhinoceros, belonging to the 
upper molar series, were described and figured by myself in the first volume of this 
series, 3 under the name of Acerotherium perimense. It, however, unfortunately 
happened that these teeth were wrongly placed in the series, and that some were 
classed as molars, which were really premolars. Although this error has been cor- 
rected in the preface and revised description of the plates of the first volume, it has 
been partly the cause of other errors, and the foundation of some unnecessary species. 
In the same volume there were also described and figured two incomplete upper 
molars of a Siwalik rhinoceros, under the name of R. planidens, 4, on the supposition 
that they belonged to a new species ; while, not long after, some complete upper 
molars, an upper incisor, and the greater portion of a mandible were noticed in the 
“Records” 5 under the same name. After all these notices had appeared, the 
discovery by Mr. Theobald of a nearly complete cranium of a hornless r hin oceros', 
together with a separate but more complete specimen of the upper molar dentition, 
alluded to in the “Records,” 6 conclusively showed that all the specimens referred to 
the so-called R. planidens in reality belonged to Acerotherium perimense , and also 
confirmed the generic distinctness of this form. These specimens, moreover, showed 
the error which had been made in the serial determination of the previous specimens 
described by myself under the latter name. In the preface and reissue of the 
description of certain of the plates of the first volume of this series, all the above- 
mentioned errors were corrected. 
In the same volume, 7 two upper molars and the occiput of a rhinoceros from 
Burma were described and figured under the name of R. iravadicus , as they could 
not then be referred to any of Ealconer’s species. Now, however, the new specimens 
have rendered it certain that these specimens likewise belong to Acerotherium 
perimense , though to a small-sized variety. It required the large series of specimens 
now possessed by the Indian Museum to show that the variations from a common 
standard occurring in many of these teeth were merely varietal forms. The two 
specimens of milk-molars figured in figure 4 of plate V of the first volume, and 
referred in the preface to R. iravadicus will also be shown in the sequel to belong, 
in all probability, to A. perimense. In consequence of the above re-determinations, 
1 “Cat. Fos. Hem. Vert., Mus. A. S. B.” Calcutta, 1859, p. 195. 2 Vol. I, p. 171. 3 P. 51, pi. VI, figs. 2, 5. 
p. 41, pi. V, figs. 7 and 9. 5 Vol. XI, p. 95- 6 Vol, XII, p. 47. 7 P. 18, pi. V, figs. 1, 2, 3. 
