868 
ELEMENTS OF GEOLOGY. 
not have been derived from the destruction of older strata, 
since in bone-beds, in general, many of the organic remains 
are undoubtedly derivative. 
Triassic Mammifer, — In North-western Germany, as in 
England, There occurs beneath the Lias a remarkable bone 
breccia. It is filled with shells and with the remains of fish¬ 
es and reptiles, almost all the genera of which, and some 
even of the species, agree with those of the subjacent Trias. 
This breccia has accordingly been considered by Professor 
Quenstedt, and other German geologists of high authority, 
as the newest or uppermost part of the Trias. Professor 
Plieninger found rn it, in 1847, the molar tooth of a small 
Triassic mammifer, called by him Mlcrolestes cmtiquus. He 
inferred its true nature 
from its double fangs, 
and from the form and 
number of* the protu¬ 
berances or cusps on 
the flat crown ; and 
considering it as pre¬ 
daceous, probably in- 
Fig. 3S9. 
i.1- 
I- 
Microlestes antiquus, Plieninger. Molar tooth, mag- 
r., • Diegerloch, near Stuttgart, 
nitiecl. Upper Trias. 
Wiirtemberg. 
a. View of inner side ? b. Same, outer side ? 
in profile, d. Crown of same. 
c. Same sectivorous, he called 
it Microlestes from /xl- 
icpoc, little, and \Tq(jTr)Q^ a beast of prey. Soon afterwards he 
found a second tooth, also at the same locality, Diegerloch, 
about two miles to the south-east of Stuttgart. 
No anatomist had been able to give any feasible conjec¬ 
ture as to the afiinities of this minute quadruped until Dr. 
Falconer, in 1857, recognized an unmistakable resemblance 
between its teeth and the two back molars of his new genus 
Plagiaulax (Fig. 306, p. 327), from the Purbeck strata. This 
would lead us to the conclusion that Microlestes was marsu¬ 
pial and plant-eating. 
In Wiirtemberg there are two bone-beds, namely, that con¬ 
taining the Microlestes, which has just been described, which 
constitutes, as we have seen, the uppermost member of the 
Trias, and another of still greater extent, and still more rich 
in the remains of fish and reptiles, which is of older date, in¬ 
tervening between the Keuper and Muschelkalk. 
The genera Sauriehthys^ Ilybodus^ and Gyrolepis are found 
in both these breccias, and one of the species, Saurichthys 
Mongeoti^ is common to both bone-beds, as is also a remark¬ 
able reptile called Notliosaurus mirahilis. The saurian called 
Belodon by H. von Meyer, of the Thecodont family, is an¬ 
other Triassic form 
lestes. 
associated at Diegerloch with Micro- 
