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SCIENCE PROGRESS. 



Michelotti, and was described by him in 1877. The fossils 

 were determined as of Silurian age, and the schists below 

 the limestones were therefore assigned to the Archean. 

 The late Melchior Neumayr re-examined Michelotti's 

 specimens, which are now in the Pisa Museum, and deter- 

 mined them as Cretaceous. The fossils, however, had 

 never been found in situ, and it was therefore very doubt- 

 ful how far they could be relied on in determining the age 

 of the Calcaire du Brianconnais, of which this Chaberton 

 limestone is the main constituent. There were six distinct 

 theories, which may be tabulated as follows : — 



The authors of the present paper therefore made a 

 further search and found not only better fossils, but the 

 exact horizon from which they come. The fossils con- 

 firm Neumayr's view of the Cretaceous age of the fauna. 

 The authors, however, find that the fossiliferous limestone 

 occurs let down by faults into the dolomites, and is there- 

 fore of more recent ao;e than these. There can be no 

 doubt that the dolomite is Triassic, and the authors there- 

 fore separate from it the coral reefs and shelly limestones 

 under the name of the Clos des Morts Limestones. 



The determination of the age of these limestones, and 

 the occurrence of a third fossiliferous zone (the radiolarian 

 phthanite of Cesana) at a lower horizon on the opposite 

 side of the Dora Valley, enables a more definite opinion to 

 be expressed as to the age of the igneous rocks of the 

 " pietre verdi" series. These form one of the most striking 

 features in the geology of the Cottians. They are doubt- 



