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28
SIK E. OWEN ON THE UPPER
4. Note on the E.esemblan'ce of the Uppee Molae Teeth of an
Eocene Mammal (NEOPEAGiArLAx, Lemoine) to -those of
Teittlodon. By Sir Eichaed Owei^, K.C.B., F.E.S., P.G.S., &c.
(Eead .S"oveinber 19, 1884.)
Shoetlt after the communication to the Geological Society of the
paper on Tritylodon * I was favoured by the author, Prof, Lemoine,
with a copy of his ' Memoire,' " Etude sur le Neoplagiaulax de la
Eaune Inferieure des Environs de Eeims " t. The chief interest of
that ' Memoire ' was, to me, the dental characters of the small
mammal there discovered, especially those of the upper molar teeth ;
while the general characters of the dentition, by their resemblance
to those of the Mesozoic Plagiaidax, are also notably suggestive J.
With a premolar, in relative size, shape, and sculpturing of crown,
so closely repeating the peculiarities of that tooth in our Oolitic
marsupial as to have suggested the generic name of the lower
Eocene mammal of Eeims (Neoplagiaulax), were associated true
molars more nearly resembling, in those of the upper jaw, the
corresponding teeth of Tritylodon than did the teeth of the
geneisi 2Iicrolestes and Stereognathus with which I compared them §.
Eigs. 1-3. — Upper Molars of I^eoplagiaulax eocsenus, Lemoine, after
Lemoine, Bull. Soc. Geol. Fr. ser. 3, torn. xi. pi. vi. Jigs. 17 Uy
17 I, Si^ 17 e.
Fig. 1. Eig. 2. Eig. 3.
^^^^ ^^f ^^^
a
1. From beneath. 2 & 3. From the sides. a. Natural size.
The figures 11 u, 17 I, 17 e, pi. vi, of M. Lemoine's 'Memoire'
appended to the present note, will enable the resemblance of the
upper molars of Neoplagiaidax eoccenus to those of Tritylodon to be
appreciated. In size the diiference is almost as great as that shown
by the molars of Microlestes \\. And here I may observe that, as
the lower molars of Neoplagiaulaar have only two longitudinal series
of tubercles, it suggests a surmise that the lower molars of Tritylodon
may be found to present the same less complex character as com-

• Quart. Journ. Geol. Soc. Feb. 1884, vol. xl. p. 246, pi. vi.
  

t Bulletin de .a Societe Geologique de France, 3e serie, t. si. p. 249.
\ Compare " pi. v. figs. 1-3," with figs. 9 and IG, pi- iv. of my " Extinct
Marsupials of England," pp. 75-87, in the ' Extinct Mammals of Australia,'
4to, 1877, p. 75.
§ Locfcit pp. 150, 151.