﻿1850.] CATULLO ON THE RED AMMONITIC LIMESTONE. 69 



inclined ledges, as well as table-lands (plateaux), sometimes nearly 

 horizontal (southern slopes of Monte Valdart in the district of Bel- 

 luna). This formation may, as we have said, be considered to be 

 composed of two distinct limestones ; one of which does not every- 

 where preserve the same characters, but presents a diversity of colour 

 and structure ; while the other, which covers the former, is almost al- 

 ways of a dark red, sometimes approaching to yellowish, although in 

 some places it loses the arenaceous appearance and assumes the schis- 

 tose structure, and it is then that, when moistened by the breath, it 

 gives out a strong argillaceous odour. In various places the inclination 

 of the strata of both these limestones is as much as from 40 to 45 de- 

 grees (between Igne and Pirago in the district of Belluna), while in 

 other places the strata are somewhat less steep, and sometimes even 

 lie in a position little removed from the horizontal (Fastro, not far from 

 Cismone in the Feltrino, Lavazzo, &c). I call the first of the above- 

 mentioned rocks the inferior epiolitic limestone, and I distinguish 

 the second from it by the name of the superior epiolitic limestone ; 

 by which I endeavour to rectify the mistakes that have naturally 

 arisen from considering these rocks as belonging to one and the same 

 formation. This distinction, partly mineralogical and partly geo- 

 gnostical, naturally leads one to suppose that the greater or less ad- 

 hesion of the fossils of the said limestone depends on the mineralo- 

 gical character of the rock ; for those found in the schistose limestone, 

 enclosed as they are in a marly coating, are easily disengaged ; while 

 the fossils of the lower limestone (which is always compact and admits 

 of a polish) adhere to it so closely that they may be said to be 

 almost incorporated with it. 



Lower Epiolitic Limestone of the Venetian Alps. 



I beg you, Sir, to direct your attention for a moment to the fossils 

 contained in the oldest of these limestones, making the different 

 Ammonites that are peculiar to them your especial guide, and passing 

 over for the present the remains of animals of other genera that pass 

 from the level of this rock to that of the superincumbent rocks. 



If the Ammonites Font ana, the Ammonites Toblinianus, and other 

 species of the same genus, which I believe to be unpublished, were 

 not found associated with some few others already published by 

 D'Orbigny, I should not be able, guided by them alone, to pronounce 

 any judgement on the age of the limestone containing them ; but 

 their being fortunately associated with well-known species authorizes 

 me to believe them to belong to a formation anterior to that of the 

 schistose limestone, with which it has been confused. 



Ammonites perarmatus, Sow., A. annulatus, Sow., A. biplex, Sow., 

 and A. linguiferus, D'Orbigny, are well-known species that might 

 throw some light on the matter in question, if it were not that in 

 some countries they are found existing in formations belonging to 

 different periods. In fact, Ammonites perarmatus and A. biplex 

 have been found by the Baron von Buch in the coralline limestone 

 of Switzerland, which is considered to be coeval with the coral rag ; 

 Ammonites linguiferus has been referred by D'Orbigny to the lower 



