1884. ] Geology and Paleontology. 817 
These points, together with the natatory limbs, indicate that the 
position of this group is with the order or suborder Pythonomorpha. 
The characters which distinguish it are, the distinctness of the 
anterior pieces, which may be called, for the present, alisphenoids ; 
the amphiplatyan vertebrz, and the presence of condyles of the 
phalanges. The Choristodera will be distinguished by these 
characters wherever placed. 
The dentition is remarkably like that of the bony gar, Lepi- 
= dosteus, and Dr. Lemoine has enabled me to identify specimens 
i zia whose place I have, hitherto been greatly pùzzled.—Æ. D. 
Eeer 
THE FORMATION OF STATUARY MARBLE.—From numerous ex- 
periments conducted separately by MM. Berthelot, Bonssingault 
and Dieulafait, it appears that the chalk must be very rich in 
Manganese. Fifty-six examples from the chalk of the Paris 
basin, Operated upon last year, gave this result without exception, 
and twenty examples from England and various parts of Europe, 
have since then yielded the same results in the hands of M. 
Dieulafait. The presence of manganese was evident in half a 
ramme of chalk. Manganese is also found ina state of com- 
piete diffusion in the marbles of Carrara, Paros and the Pyrenees. 
Important geological consequences result from the discovery. 
ven as low as the lower gneiss, limestones exist, often arranged 
be come lost in the enclosing rock, This arrangement 
Proves that the cipolins are cotemporaneous with the rocks en- 
Closing € examination of samples of the rocks from 
ese, the iron will be precipitated almost pure, while the Saeed 
ass would dis- 
uid be deposited in concentric layers in the midst 
Ssic rocks. 
