, 
408 Notices of British and Foreign Memoirs. 
glodonts, and as driving the colossal American species to seek their 
prey along or upon the sea-shore. For a second generic dis- 
tinction Prof. Van Beneden relies upon a difference in the number 
of the teeth. He admits, however, both American and European 
Zeuglodonts to be essentially carnivorous Cetaceans; and every 
experienced student of such, from John Hunter downwards, had 
observed the variability of the number of teeth in individuals of the 
same species. Supposing that the present known portions of jaws 
and an entire unbroken maxillary or mandible of a Zeuglodont had 
never yet been found to support our author’s conelusion—that the 
Huropean Zeuglodonts have five double-rooted, serrate-crowned 
molars on each side of both jaws, in addition to the number of those 
in the American Zeuglodont (p. 62),—the question then arises, 
whether this dental character should be regarded as of higher im- 
portance than it is held to be in equally natural genera, or groups of 
existing carnivorous Cetacea, in which the numerical differences in 
similarly shaped teeth are noted amongst the specific characters. 
The teeth of both the European and American Zeuglodonts con- 
sist of anterior laniariform, single-rooted, and posterior lamelli- 
form, serrated, and two-rooted: in both, the first six are incisors, 
by reason of their implantation in the intermaxillary bones. But 
M. Van Beneden affirms that the foremost incisor extends on the 
axis of the body in the European Zeuglodont, and curves down- 
ward in the American—a difference which we do not believe can be 
absolutely predicated from the portions of the skull of the great 
American species hitherto examined. But, if admitted, and shown to 
be not related to the age of the individual, it may be questionable 
whether different directions of growth of homologous teeth should 
support generic distinction; for, if so, how many genera might not 
so be characterized out of the Elephants of India alone! 
Admitting, however, for the sake of convenience, that the 
differences, so far as they appear to be shown by the mutilated 
remains of the Zeuglodont Cetacea, may be expressed by generic as 
well as specific differential terms, we have then to submit that the 
name Phocodon ought, on the ground of priority, to be given to the 
smaller European kind. 
Prof. Van Beneden admits that the name Basilosaurus, proposed 
in 1832 for the American kind, was ‘malheureusement trop sig- 
nificatif, and agrees with Harlan and myself in the change of name 
to Zeuglodon, which, since 1839, has been adopted; but, while 
characterizing the name Squalodon as being ‘également trop 
significatif, he adds, ‘Nous ne voyons aucun motif plausible pour 
changer le premier nom qui lui a été imposé par Grateloup’ (p. 4). 
The motive, more than plausible, for not adopting Squalodon, is, 
that it has neither priority as regards the Zeuglodonts generally, 
nor as relating to European Miocene Zeuglodonts in particular. 
With much greater reason we may use the words of M. Van Beneden 
—‘ We see no plausible motive for changing the first name which 
had been imposed’ upon the European Zeuglodont by Agassiz. 
True, indeed, that name also was too significative of the conclusion 
