42 JOURNAL OF COMPARATIVE NEUROLOGY. 
but whether to the same species or even genus as the other 
specimen must at present remain an open question. 
Mr. BEADNELL kindly placed this specimen at my disposal. 
The size and relative proportions of the different parts are 
almost identical in the two casts. Nevertheless, there are a 
considerable number of differences, some features being dis- 
played in one and not in the other, and wee versa. Many of 
these differences are obviously due to the imperfections of the 
casts, and especially to the failure of the plaster mold to repre- 
sent the true form of the brain. But there are several peculli- 
arities of the natural cast—such, for example, as the form of 
the caudal part of the cerebellum and the shape of the cerebral 
hemispheres—which are difficult to reconcile with the artificial 
mold, even if we admit that the inner face of the cranium 
(from which the latter was made) is damaged or imperfectly 
cleaned. The differences, nevertheless, are sufficiently pro- 
nounced to indicate a generic distinction between the two speci- 
mens; and in this connection it is interesting to recall a state- 
ment made by Dr. AnprReEws in his first reference to Zeuglodon, 
as ‘including apparently Damers’ Z. Osiris, and perhaps a 
second species.”’’ It would, however, be very unwise, because 
it would serve no useful purpose, and possibly lead to error, to 
found a new genus or even a new species on the evidence of 
this natural cranial cast, when our source of information con- 
cerning the known genus (Zeug/odon) is as unsatisfactory as that 
obtainable from the artificial one about to be described. More 
especially so, when it is remembered that in the case of the 
only indisputable facts (z. e., size and general form) the two 
casts are agreed. [shall therefore merely describe and attempt 
to explain the meaning of the form of the two specimens, and 
leave the question of the specific identity open for future re- 
search. 
The general appearance of the brain is extraordinarily 
peculiar (figs. 1 and 2). The shape of the anterior part of the 
natural cast (fig. 1, @ and 6) closely resembles the cerebrum of 
1 ‘Geological Magazine,’ September, 1901, p. 401. 
