1850.] ZIGNO ON THE VENETIAN ALPS. 429 



For besides the many new species described by M. Catullo, we find 

 several well known as characteristic of the * craie chloritee.* 

 The new species of M. Catullo are as follow ; — 



Nerinsea Borsoni, Bronn. Hippurites imbricatus, Cat. 



Hippurites nanus, Cat. Zoveti, Cat. 



contortus, Cat. Sphserulites duplovalvata, Cat. 



maximus, Cat. umbellata, Cat. 



fasciatus, Cat. Da Rio, Cat. 



rugulosus, Cat. Gazola, Kefst. 



Fortisii, Cat. Baculites Alpaghina, Cat. 



Turricula, Cat. flexuosa, Cat. 



dilatatus, Cat. 



Those which determine me to classify this bed with the upper 

 greensandjOr 'terrain Turonien' of M.d'Orbigny, are the following: — 



Acteonella laevis, Sow. sp. Hippurites cornu-pastoris, Desmoul 



gigantea, Sow. sp. organisans, Desmoul. 



Actaeon ovum, Duj. sp. Radiolites Ponsianus, D'Jrchiac, sp. 



It appears to me impossible, on palseontological grounds, to admit 

 of any classification of this deposit different from that which I pro- 

 pose, and which confirms what M. d'Orbigny long ago advanced, viz. 

 that the Rudistes of Italy were confined to his third zone. Previous 

 to my discovery of the true Neocomian beds, the Rudistes of this 

 part of Italy had been considered of Neocomian age ; but they have 

 been placed even below the ammonite limestone which abounds in 

 Jurassic fossils. When, however, M. von Buch at the meeting at 

 Milan established the true place of the ammonite limestone among 

 the oolites, these hippurite beds of Santa Croce were confounded with 

 the scaglia, which scaglia palseontological reasons force me to consider 

 as upper cretaceous, or 'terrain Senonien.' 



The upper cretaceous group of this country consists either of a 

 brick-red, sandy limestone, or of a red, white, or grey argillaceous 

 limestone, called by Italian geologists Scaglia. It is characterized 

 by true chalk fossils, such as Ananchytes ovaia, Lamk., A. tuber- 

 culata, Defr., Holaster natica^ Inoceramus Cuvieri^ Sow., I. La- 

 marckii. Park. The beds vary in thickness, but are usually thin, 

 fragile, and almost schistose, from whence its name of Scaglia. They 

 pass downwards into grey beds with dark spots, occasioned by fucoids. 

 Sometimes a black bituminous limestone occurs subordinate to the 

 formation.. 



This is the group which everywhere in these Alps forms the base 

 of the cretaceous system. Without the help of fossils it would have 

 been difficult to have traced these limits on account of the general 

 conformability of the strata from the lowest beds of the trias to the 

 most recent, which obliges us to admit of a vast period of tranquillity 

 in this portion of Europe. It is true that during their deposition 

 eruptions have taken place which have fractured them and occasioned 

 the formation of conglomerates ; but these eruptions have been very 

 partial, and are nowise connected with the great upheaval, which has 

 been occasioned by the igneous rocks of the Tyrol. The partial 

 eruptions of melaphvre, dolerite, basalt, trachyte, &c., have caused 



2 H 2 



