1888.] NATURAL SCIENCES OF PHILADELPHIA. 293 



Amphilestes with six molars and Triconodon Avith four. The second 

 specimen, a left ramus also seen upon the outer surface, has three 

 premolars f». situ and the space for a fourth, (7?3»i ); in front of 

 this is a deeper alveolus, probably for the canine, preceded by the 

 alveoli of at least three incisors, so that the lower dental formula 

 may now be given Avith considerable certainty as follows: 



i- h-, CuPi, me. 

 The canine is not preserved. The premolars as viewed upon the 

 outer surface have prominent cingules but not the true basal cusps 

 seen in Triconodon. The outer face of the molars is entirely devoid 

 of a cingulum. None of the specimens give any evidence that the 

 angle is distinct, but indicate that the lower border rises to the level 

 of the condyle precisely as in PhascoJotheriuvi, Spahicotherium and 

 Triconodon. This strengthens the writer's reference of these genera 

 to one family as opposed to the views of Marsh and Lydekker; never- 

 theless, as shown below, Spalacotherium is a more specialized type 

 than the others. 



PHASCOLOTHERIUM. 



Besides the type in tlie British ^Museum there is a beautifully 

 preserved specimen belonging to this genus in the Oxford Museum 

 and through the kindness of Mr. James Parker of Oxford the writer 

 had an opportunity of examining a third specimen in his private 

 collection. The latter, which has been figured in Phillips' "Geology 

 of Oxford," is remarkable for the extension of the coronoid beyond 

 the vertical line of the condyle. The Oxford INEuseum specimen^ 

 contains only the four posterior molars, probably nii — m-; with the 

 fangs of 5)1.2 iind m;^. It may however be readily distinguished from 

 the Amphilestes specimens by the stout cones and by the fact that 

 the internal cingulum rises in two points upon the inner faces of 

 the molars instead of in a single point beneath the protocone; also 

 by the stout character of the jaw\ 



A renewed study of the molar teetli in the type specimen shows 

 that all the post-canine teeth present the characters of molars in 

 some re-ipects. The first tooth behind the canine has a main cusp 

 like that of the posterior molars and an internal cingulum horizontal 

 and rising in two points instead of showing the sweep downwards and 

 backwards which is so characteristic of premolar cingula. The 

 accessory cusps are either covered Avith matrix or broken off. The 

 second tooth has a fractured cingulum so that one cannot determine 



1 The cavt of this specimen in the Natural Histury Museum (m. 230(1) has been 

 mistakenly referred to AmphiUstes by Lydekker, op. cit., p. 272, on the ground of 

 ■"the small development of the accessory fore-and-aft cusps." The basal cusps of 

 the molars are quite as prominent as in the type. 



