164 NATURAL HISTORY. 



quadrupeds (kangaroos, opossums, &c.) may be stated, as 

 a general rule, to have the lower jaw of a characteristic 

 form, the part of the jaw known as the ' angle ' being bent 

 inwards or 'inflected.' Correlated with this peculiar 

 structure of the jaw, but having no recognisable connection 

 with it, are two little bony splints, which are attached to 

 the brim of the pelvis, and which are known as the 

 'marsupial bones.' No exceptions were known in the 

 time of Cuvier to this rule ; hence Cuvier was entitled to 

 regard this as a constant correlation. Thus he met with 

 a fossil skeleton of a quadruped, like all such fossils, only 

 preserved in parts, which showed the lower jaw ; and find- 

 ing that the angle of the jaw was ' inflected,' he came to 

 the conclusion that it was a Marsupial. Moreover, from 

 the structure of its teeth he inferred that the skeleton 

 belonged to one of the opossums, such as now inhabit 

 the American continent, and he named it the Didelphys 

 gypsorum. 



As all living Marsupials are found in Australia, New 

 Guinea, certain of the islands of the Pacific, and in 

 North and South America, the alleged discovery of an 

 opossum in the Tertiary strata near Paris, naturally excited 

 some incredulity in the scientific world. In order to 

 dissipate this incredulity, Cuvier invited his scientific 

 colleagues to meet him, and proceeded in their presence 

 to cut away with a chisel the stone enveloping the bones, 

 so as to bring into view the front part of the pelvis, which 

 lay deeply buried in the matrix. On accomplishing this, 

 he was able to demonstrate at once that the pelvic bones 

 carried the ' marsupial bones,' which are so characteristic 

 of the opossums and of Marsupial quadrupeds in general. 



