206 MIOCENE PERIOD. [Ch. XV. 
rium magnum, Mastodon angustidens, Hippopotamus major, 
and H. minutus, Rhinoceros leptorhinus, and R. minutus, Ta- 
pir gigas, Anthracotherium (small species), Sus } Equus (small 
species), Cervus, and an undetermined species of the Rodentia. 
The first species on this list is common to the Paris gypsum, 
and is therefore an example of a land quadruped common to 
the Miocene and Eocene formations, an exception perfectly in 
harmony with the results obtained from the study of fossil 
shells *. 
Basin of the Gironde and district of the Landes. — A great 
extent of country between the Pyrenees and the Gironde is 
overspread by tertiary deposits which have been more par- 
ticularly studied in the environs of Bordeaux and Dax, from 
whence about 600 species of shells have been obtained. These 
shells belong to the same type as those of Touraine. — See Ap- 
pendix I.f 
Most of the beds near Dax, whence these shells are pro- 
cured, consist of incoherent quartzose sand, mixed for the most 
part with calcareous matter, which has often bound together 
the sand into concretionary nodules. A great abundance 
of fluviatile shells occur in many places intermixed with the 
marine ; and in some localities microscopic shells are in great 
profusion. 
The tertiary deposits in this part of France are often very 
inconstant in their mineralogical character, yet admit generally 
of being arranged in four groups, which are enumerated in the 
explanation of diagram No. 51. 
In some places the united thickness of these groups is con- 
siderable, but in the country between the Pyrenees and the 
valley of the Adour around Dax, the disturbed secondary rocks 
* For further details respecting the basin of the Loire, see M. Desnoyers, Ann. 
des Sci. Nat., tome xvi. pp. 171 and 402, where full references to other authors 
are given. 
f M. de Basterot has given a description of more than 300 shells of Bordeaux 
and Dax, and figures of the greater number of them. Mem. de la Soc. d'Hist. 
Nat. de Paris, tome ii. 
