FOSSIL MAMMALIA. 



57 



DESCRIPTION OF A FRAGMENT OF A CRANIUM OF AN EXTINCT MAMMAL, 

 INDICATIVE OF A NEW GENUS OF EDENTATA, AND FOR WHICH IS PROPOSED 



THE NAME OF 



GLOSSOTHERIUM. 



" La premiere chose a faire dans l'etude d'un animal fossile, est de reconnaitre la 

 forme de ses dents molaires ; on determine par-la s'il est carnivore ou herbivore ;" 

 says Cuvier, at the commencement of that series of splendid chapters in which 

 the restoration of the extinct Pachyderms of the Paris Basin is recorded. In the 

 present case, however, as in that of the Mammiferous animal whose fossil remains 

 we were last considering, the important organs, to which Cuvier directs our first 

 attention, are wanting. Nor are there here, as in the Macrauchenia, any remains 

 of the locomotive extremities to compensate for the deficiency of teeth, and guide 

 us into the right track of investigation and comparison. The animal, the nature 

 and affinities of which are the subject of the following pages, is, in fact, repre- 

 sented in Mr. Darwin's collection, by nothing more than a fragment of the 

 cranium. 



This fragment, which was found in the bed of the same river, (see p. 16,) in 

 Banda Oriental, with the cranium of the Toxodon, includes the parietes of the 

 left side of the cerebral cavity, the corresponding nervous and vascular foramina, 

 the left occipital condyle, a portion of the left zygomatic process, and, fortunately 

 also, the left articular surface for the lower jaw. The importance of this surface in 

 the determination of the affinities of a fossil animal has been duly appreciated, 

 since the relations of the motions of the lower jaw to the kind of life of each 

 animal were pointed out by Cuvier; but yet we should be deceived were we to 

 establish, in conformity with the generalization enunciated by Cuvier,* our conclu- 

 sion, from this surface, of the nature of the food of the extinct species under con- 



* " Comme le genre de vie de chaque animal est toujours en rapport avec les mouvements dont sa machoire 

 est susceptible, on retrouve dans la conformation des surfaces destinees a l'articulation, les particularites qui 

 semblent le determiner d'avance. Ainsi dans les animaux qui vivent de chairs, substances filamenteuses qui 

 ne peuvent etre ecrasees, mais seulement coupees et dechirees, le mouvement de la machoire inferieure ne pent 

 s'executer que de haut en bas. Dans les herbivores, les frugivores et les granivores, comme le principal mouve- 

 ment est celui de broiement pour ecraser, comprimer les herbes et les fruits, pour briser les grains et les reduire, 

 en pate, lc mouvement des machoires se fait encore dc droite a gauche, et reciproquement, on en m&me temps, 

 de devant en arriere, en un mot, dans un plan horizontal autant que dans un vertical : les uns representent des 

 ciseaux, les autres des meules de moulin." 



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