284 MARSUPIALIA. 



28134. Fragment of the left ramus of the mandible, showing 

 two true molars ; from the Upper Eocene (Lower Oli- 

 gocene) of Debruge near Apt (Vaucluse), France. 



Bravard Collection. Purchased, 1852. 



28131. Anterior portion of the left ramus of the mandible, showing 

 the outermost incisor, the canine, and the three premolars, 

 p m> 4 being not protruded from its alveolus ; from the 

 locality. Same history. 



Didelphys arvernensis, Croizet l . 



Syn. Peratlierium arvernense, Gervais 2 . 



About the size of D. affinis, from which it is stated to differ by 

 the talons in the lower true molars being tricuspid. Gervais gives 

 the length of the lower series of cheek-teeth as 0,0135 ; the maridi- 

 bular ramus is slender ; pm . 1 is small and in contact with pm. 3, 

 the latter being nearly as tall as pm. 4. 



Hob. Europe (France). 



27700. The nearly entire right ramus of a mandible containing the 

 canine and most of the cheek-teeth, apparently belonging 

 to this species ; from the Lower Miocene (Upper Oligocene) 

 of Sauvetat (Puy-de-D6me), France. The talon of in73 is 

 tricuspid, and the length of the series of cheek-teeth 

 0,0128. Croizet Collection. Purchased, 1848. 



27810. Part of a left mandibular ramus with the canine, p~m~3, p~rn74, 

 (Fig.) and m. 1, apparently belonging to the same species as the 

 preceding ; from the Lower Miocene of Cournon (Puy-de- 

 Dome). Figured by Gervais in the ' Zool. et Pal. Fran- 

 gaises,' 2nd ed. p. 264, fig. 33, and referred to D. exilis ; 

 it differs from the type specimen of the latter (No. 27806) 

 by the much more slender ramus. Same history. 



Didelphys blainvillei, Croizet '. 



Syn. Peratherlum blainvillei, Gervais *. 



Of somewhat larger size than D. arvernensis, but with the molars 

 apparently rather taller (p m . 4 is not shown in the type) and plnTl 

 relatively larger. The length of the space occupied by the four true 

 molars in the type is 0,009, and that by the last three 0,007. 



Hab. Europe (France). 



1 In Gervais's Zool. et Pal. Frai^aises, 1st ed. vol. i. p. 134 (1848-52). 



2 Ibid. 2nd ed. p. 263 (1859). 



3 Ibid. 1st ed. vol. i. p. 134 (1848-52). 



4 Ibid. 2nd ed. p. 263 (1859). 



