FOSSIL MAMMALIA FROM THE STONESFIELD SLATE. 413 



In subsequent works Owen again describes and figures this 

 jaw (20, 21, 23); a "diagram" of it is given by Professor 

 Phillips in his ' Geology of Oxford' (24). 



In 1888 Professor H. F. Osborn published his interesting 

 memoir on the ' Mesozoic Mammalia of the Old and New 

 Worlds/ in which he treats of the Amphitherium jaws (14). 

 Unfortunately the description of the molars is quite erroneous, 

 owing to the author's considering that the cusps were all in 

 the same line. " The fact is," says Osborn, " these crowns of 

 the molars consist of an elevated anterior and median cusps, 

 followed by a low posterior heel, and with an internal 

 cingulum rising into the low cusp on the inner face of the 

 median cusp." At this time Osborn had only seen drawings 

 and published figures of the Oxford jaws, but shortly after, 

 during a second visit to England, he examined them himself, 

 and corrected his mistake in a subsequent publication (15), 

 finding the external cusp described half a century before by 

 Owen. 



I have nothing to add to these descriptions, excepting the 

 fact that Owen was wrong in considering the median projec- 

 tions in molars 4 and 5 as being the external cusp (which he 

 found in molars 2 and 6) ; they are simply the surface where 

 the internal cusp has been broken off, and I have exposed in 

 these two teeth the external cusp itself, which was previously 

 hidden (see figure). 



The second specimen in the Oxford Museum (PI. 26, 

 fig. 2) is a left ramus, seen from the inside. 



Valenciennes was, I believe, the first to mention this fossil 

 (31), which was one of the two brought over to Paris by Buck- 

 land in 1838. The French author, however, erroneously con- 

 sidered it was " de la meme espece que celle decrite et figuree 

 par M. Broderip, son Didelphys Bucklandi" (Phascolo- 

 therium). 



Owen figured and described it correctly (19 — 21, 23) as 

 a left ramus containing one molar behind, separated (by a gap 

 wide enough to allow for four molars) from two entire and two 



