246 RODENTIA. 
Ctenomys, sp. 2. 
Hab. S. America. 
40675 b. The associated cranium and mandible, in a somewhat 
broken condition ; from the Pleistocene of Buenos Ayres. 
These specimens, which indicate a smaller species than 
the last, come very close to the existing C. leucodon. 
Bravard Collection. Purchased, 1854. 
Family HYSTRICID A. 
Dentition :—I. 5, C. 5, Pm. 5, M. 3. 
Genus SYNETHERES, F. Cuvier ’. 
Syn. Sphingurus, F. Cuvier ?. 
Cercolabes, Brandt °. 
The teeth of this genus can only be distinguished from those of 
Erethwzon by the circumstance that in the latter the first tooth of 
the cheek-series is considerably longer than the last, whereas in the 
former all the teeth are subequal. 
Synetheres fossilis (Waterhouse *). 
Syn. Cercolabes fossilis, Waterhouse °. 
(?) Synetheres magnus, Lund °. 
As the remains on which this species is founded do not show the 
first tooth of the cheek-series, it is impossible to say whether it 
really belongs to Synetheres or Hrethizon. On distributional grounds 
it is, however, more probable that it belongs to the former, to which 
it is accordingly provisionally referred. In size it considerably 
exceeds the existing Hrethizon dorsatus, and is therefore very much 
larger than any of the existing species of Synetheres. 
Hab. 8. America. 
18869. Two fragments of the opposite rami of the mandible; from 
the caverns of Minas Geraes, Brazil. The more perfect 
specimen shows the three true molars, and the less perfect 
1 Mém. d. Muséum, vol. ix. p. 413 (1822), Synéthére. 
2 Loe. cit., Sphingure. 
5 Mém, Ke, Imp. St. Pétersbourg, ser. 6, vol. iii. p. 391 (1835). 
* Natural History of the Mammalia, vol. ii. p. 486 (1848), Cercolabes. 
5 Loe. cit. 
®° K. Danske Vid. Selsk. Sky. vol. vii. p. 250 (1840). 

