418 E. S. GOODRICH. 



In his writings on this jaw Owen describes the rounded and 

 sweeping outline of the lower margin, the wide recurved coro- 

 noid process resembling that of the " zoophagous Marsupials/' 

 the notch between the coronoid process and the condyle being 

 especially like that in Thylacinus. Other resemblances he also 

 finds to Thylacinus, namely, in the inflected angle and the 

 molars, whilst the condyle is said to be more like that of 

 Dasyurus and Didelphys. A well-marked mylohyoid groove 

 is present, and the dental foramen is far forward, as in other 

 related Mesozoic mammals. Owen claims that the ^^ molars" 

 (grinders or cheek-teeth) of Phascolotherium resemble those of 

 Thylacinus in number (seven in both cases) and in shape, both 

 possessing three main cusps in a line and two accessory fore- 

 and-aft cingulum cusps, very small in the case of the living 

 Marsupial. He could distinguish no difference between pre- 

 molars and molars, and looked upon the grinding teeth as 

 being in a simple condition in which the two varieties were 

 not differentiated. 



All observers have noticed the peculiar pitting of the surface 

 of the grinders of Phascolotherium. ^ Osborn, in his first 

 paper, also held the view that the seven grinders could not be 

 distinguished into premolars and molars : '^ A close study of 

 m. 1 shows that it possesses in miniature the characteristic fea- 

 tures of the other molars, three cusps and a basal cingulum" 

 (14). In the ^Additional Observations' (15), after examining 

 all the specimens of this species, he writes, '' 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 back- 

 wards which is so characteristic of premolar cingula. The 

 accessory cusps are either covered with matrix or broken oflp. 

 .... The chief interest lies in the main cusp [of the second 

 tooth], which is loftier and more pointed than the protocone 



^ It is interesting to notice that the teeth of Phoca barbata, which 

 resemble them so closely in shape (as pointed out by Agassiz, 1), also exhibit 

 a pitting of the surface, which might lead one to believe that they are both 

 adapted to some similar kind of food. 



