﻿SECONDARY MARSUPIALS. 273 



Other Tertiary Marsupials in either Europe or North America, 

 thus justifying the conchisions arrived at above as to a former 

 connection between South America and Austraha. 



An interesting anecdote in connection with the demonstra- 

 tion of the affinities of Didelphys gypsorinn of the gypsum 

 quarries of Montmartre, as detailed by Owen, may be appro- 

 priately introduced here. The affinities of this fossil were 

 originally deduced from the characters of the jaws and teeth ; 

 " but these were associated with other parts of the skeleton in 

 the same block of stone." When Cuvier expressed his con- 

 victions of the Opossum nature of the fossil from the parts 

 first examined, his scientific associates were incredulous. He 

 invited them, therefore, to witness a crucial test. On the slab 

 containing the jaws and teeth, the outline of the back part of 

 the pelvis was also exposed, the fore part being buried in the 

 matrix. By his delicate use of the graving-tool, Cuvier 

 brought to light that part with the two Marsupial bones in 

 their natural position. He thus demonstrated that there had 

 been buried in the soft fresh-water deposits, hardened in after 

 ages into the building-stone of Paris, an animal whose genus 

 at the present day is peculiar to America. 



FAMH.Y TRICONODON ITD.^. 



The whole of the remaining families of the Marsupials are 

 mainly confined to the Secondary rocks, although a few sur- 

 vived into the earliest portion of the Tertiary period. All are 

 of small size, and some are extremely minute. 



In the present family the molar teeth, as shown in Fig 3 of 

 the accompanying diagram, consist of three simple compressed 

 and cutting cusps arranged in the same longitudinal Ime ; 

 the upper teeth biting on the outer side of the lower ones. 

 In the upper jaw the number of teeth is unknown, but in the 

 lower jaw there were three pairs of incisors, one of canines, 

 3 X 



