Recent Literature. 235 
that when the outer faces of the lower molars are known they will 
also prove to be of the Stylodon type. The Amphitheriide is thus 
made a miscellaneous family, to embrace genera with lower molars 
—multicuspidate, tricuspidate, or differentiated into a blade and 
talon.” “ The difference in the character of the lower molars is not 
greater than obtaining in the Dasyuride” (p. 269). 
While this may be true, it does not afford sufficient ground for 
separating Phascolotherium and Amphilestes from genera with three- 
lobed molars (Triconodon) and placing them with genera with two- 
lobed molars (Amphitherium and Peramus). The American genus ` 
Dromatherium, with unpaired fangs, is also placed in this family, ' 
adding to its heterogeneous character. 
(2.) Triconodontide, Triconodon, probably by a typographical 
error, is stated to have no internal cingulum upon its molars (p- 
257). The cingulum is one of the most characteristic features of 
the molars, and establishes the close homology which exists between 
the Triconodon, Phascolotherium, Amphilestes and Spalacotherium 
molars, indicating their phylogenetic relation with many mandibular 
and dental characters in common, that they formed a series of primi- 
tive Carnivora. Lydekker follows Marsh® and Osborn® in making 
scotherium the type of a distinct family, the (3) Spalacotheriide. 
+he inward rotation of the lateral cusps characteristic of this genus 
ìs begun in Phascolotherium and extended in Tinodon, affording tran- 
sitions ; so that, with the resemblances of the mandible and pre- 
molars, it is probable that this genus is an offshoot of the Tricono- 
type. At all events, I cannot now discover family characters. 
sufficient to separate it from the Triconodontide. I cannot share 
the opinion (p. 292) that these molars are of the Chrysochloris type; 
h are rather of a primitive tubercular, sectorial order, leading to 
. sectorial triangle of the Didelphys molar. Upon page 294 we 
a. Peralestes (type maxilla, Owen) also placed in this family, and 
“eae A separated as a genus from S. tricuspidens. The molars 
i genus, with separate external and internal cusps, are widely 
np from those of Spalacotherium, the upper molars of which 
mi probably be found to exactly reverse the pattern of the lower. 
'S genus seems, therefore, to be identical with Peraspalax. 
(+) It is in Stylodon, type of the Stylodontide, that we find the 
ay omologue of the Chrysochloris molar® and a representative 
qro ttue line of Insectivora. Lydekker, although in possession of 
: ay s description of the lower molars of the closely allied genus 
éj jo'estes, describes the lower molars of the Stylodontidæ as simply 
nical (p. 290). We have positively no grounds for referring this 
1 I os 
» It is probable that several specimens which were referred to 
Cenblotherium by Owen really balone to Stylodon—e.g., A. mustelula 
Fig. 2, Owen’s Memoirs). The mandibular and premolar 
Trylodonti, f this genus and Achyrodon is very similar to some of the 
de. See Achynodon Names, Owen, Plate II., Fig. 7. 
