2o Recent Literature. 
interest. The chief point is the question of phylogeny. In my 
opinion, the Multituberculata will finally prove entirely distinct 
from the Diprotodonts and representative of a phylum of genera 
which reached too great a degree of specialization at the close of the- 
Cretaceous to survive until the recent period. Thylacoleo was placed 
as the latest representative of the Plagiaulax line by Owen, and,. 
later, by Cope; but this view is not shared by Lydekker, who 
places it near the Phalangistide. (Op. cit., p. 188.) ` 
e family arrangement is the same as that proposed by Cope 
and adopted by myself,! with the addition of the Bolodontide. We 
are surprised to find Microlestes placed in the latter family instead 
of in the Plagiaulacide ; for the type-molars bear only a superficial 
resemblance to those of Bolodon, and closely approach those o 
Plagiaulaz. 
The Polyprotodont genera are provisionally placed by Lydekker 
in five distinct families, under the Marsupialia Polyprotodontia.. 
In the arrangement of these genera the author has been at a great 
disadvantage in not having been able to study the types of the Yale 
College collection, in which the molars are exposed upon both the 
inner and outer surfaces, and thus fails to recognize the distinctive 
features of the molars in many instances. But this will not explain 
his separation of Amphilestes and Phascolotherium from the Tricono- 
don line and their union with such diverse forms as Amphitherium, 
Achyrodon and Peramus. 
1.) In the Amphitheriidee (which embraces, among others, the five 
genera just mentioned) we are surprised to find (p. 274) that Peras- 
ax is made a synonym of Amblotherium. This is explained ina 
footnote (p. 274), in which a small inner cusp is described upon the 
ower molars of A. soricinwm—an interesting observation if correct, 
use it is entirely opposed to the observations of Owen (Mesozoic: 
Mammalia, 1871) and the writer (1886). According to the latter, 
eraspalax has prominent internal cusps, separate from the internal 
—a type of molar found only in the type maxilla of Peralestes. The 
lower jaw of Peralestes, type of Phascolestes (Owen), is also united 
with Amblotherium. This is more probable, as the outer face of 
neither genus is certainly known, and the inner faces are very simi- 
lar ; but if Amblotherium and Phascolestes are alike, both must be re- 
1On the Bireta and Classification of the Mesozoic Mammalia. Ab- 
stract, Proc. Phila. Acad., June, 1887. 
2 Am. Jour. Se. and Arts, April, 1887. 
