18 FOSSIL MAMMALIA OF THE 



part or ' angle ' is continued more directly from tlic inner end of the condyle, and, being 

 broken away, its base constitutes the ridge which runs forward, bounding below the large 

 shallow depression on the inner side of the ascending ramus. Viewing the under surface of 

 that ramus in Sarcoj>hiIus and Tki/Iacinus, the flattened plane formed by the inbent angle 

 inclines from without inward and rather downward (see Cut, fig. 5, p. 73) ; in Phascolothe- 

 ritim the slope of the same part is rather upward and inward ; so that it needs the mylo- 

 hyoid groove (ff) and symphysis (.s) to convince one that it is the inner and not the outer 

 surface of the ramus which is exposed. The entry to the dental canal {d) is more advanced 

 in position than in the existing Australian genera above cited. The coronoid process in 

 direction and proportion and in the depth of the notch between it and the condyle resem- 

 bles that in T/iylaciiufs move. \\\m\ that of Sarcopliihts ; but the anterior border is more 

 convex, the fore-and-aft breadth is relatively greater, and the posterior apex a little more 

 produced. In the gentle cin*ve by which the lower margin of the mandible is continued to 

 the incisive alveoli, Pliascolothcrimii more resembles Phasco(/ale than it does TJtylacinus or 

 Sarcopliihis. 



The mylohyoid groove is narrow and sharply defined ; it runs from below the entry 

 of the dental canal almost straight forward and downward, terminating at the under 

 border below the third molar tooth ; it has been mistaken for a suture, and looks very 

 like one, but the bottom of the groove is entire. In size this fossil mandibular ramus 

 equals that of the existing marsupial Phascogulc jjeiiicillata. 



The specimen of Phascolofherhim Bucklandi above described is in the British 

 Museum. 



§'V. — Genus — Stereognathus, Charlestcorth} 1S54. 

 Species — Stereognathus ooliticus, C/i. PI. I, figs, il — 30. 



The fact of a genus and species distinct from any mammalian fossil at that time got 

 from deposits ofMesozoic age was made known by Edward Charlesworth, Esq., F.G.S., 

 to the Geological Section of the British Association at the meeting at Liverpool in 1854. 

 But there appears to be no record of generic or specific characters. 



The fossil itself was submitted to me for description,^ at IMr. Charlesworth's instance, 

 by its possessor, the Rev. J. P. B. Dennis, M.A., F.G.S. It consists of a portion of jaw 

 with teeth imbedded in a slab of the Oolitic slate of Stonesfield, Oxfordshire. 



The portion of bone exposed to view is about nine lines in extent, and is part of a 

 ramus of the lower jaw, containing three molar teeth (PI. I, figs. 27 and 27 a). It is 

 nearly straight ; the side exj)0scd is convex vertically, which indicates it to be the outer 

 side ; a slight increase of vertical diameter towards the end (a) indicates it to be part of a 



1 'Report Brit. Assoc' (Liverpool), 1854, Rep. Sect., p. 80. 



^ See 'Quarterly Journal of the Geological Society of London,' vol. xiii (1857), pp. I, &c., pi. i. 



