Correspondence — Mr. G. A, Lehour. 



423 



3. Calcaire gris (not gres) : The ornamental marble of Saltrio, con- 



taining Ammonites Bucklandi. 



4. Calcaire noir : The black marble of Varenna. This is the base of 



the " Jura Lombard." Beneath it occur in places, and especially 

 between Lakes Lugano and Como, (5) some extremely interesting 

 black fossiliferous shales, which have been referred to the St. 

 Cassian Group by Escher v. d. Linth. Below these again comes 

 6. The Gonglomerat marneux : in which fossils are not known, but 

 which is referred to the Keuper horizon by Omboni. 

 How very diiferent a set of deposits we have here from anything 

 to be found in England between Trias and Neocomian will be seen 

 at once ; but if an attempt at correlation could serve any useful pur- 

 pose, it would be something like this : 



Biancone. 



Lower Neocomian of Speeton. 



Majolica. 



Portlandian. 

 Kimmeridgian. 

 Corallian. 

 Oxfordian. 

 Lower Oolite. 



Calcare rosso ammonitifero 

 ( = Calcaire rouge) . 



Upper, Middle, and Lower Lias (in 

 part). 



Marmo di Saltrio 

 ( = Calcaire gris). 



Lower Lias {Ammonites oxynotus and 

 Amm. Bucklandi horizons). 



Calcare degli stampi ( = Calcaire noir) . 



White Lias. 



Guggiate Beds. 



Ehsetic. 



Green and Eed Marls (= Conglomerat 

 marneux). 



Keuper. 



It should be noted that all these divisions are perfectly conform- 

 able, and that, notwithstanding the very marked difference in colour, 

 the white majolica and the red ammonite bed are, palasontologically 

 speaking, one continuous whole. 



Much information (and extremely varied, for no two, of the earlier 

 authors at least agree in their interpretation of the facts) on this 

 subject will be found in the papers of Pasini, Catullo, Curioni, de 

 Eilippi, de Collegno, Omboni, etc. From a paper by the last-named 

 geologist, much of the above matter is taken. 



The " Calcare rosso " of the Apuan Alps, the vicissitudes of which 

 I described in 1876,^ appears to be probably the equivalent of the 

 Marmo di Saltrio. G. A. Lebouk. 



2, WooDHOusE Terrace, Gateshead-on-Tyne. 



1 " The Carrara Marbles," Geol. Mag., Decade II. Vol. III. p. 289. 



