Structure of the Eastern Alps. 361 



without exception the myriads of shells are in a state of calcination and not 

 of petrifaction. In these respects they resemhle tlie tertiary groups of the 

 Hampshire coast and the Isle of Wight. In the lower group most of the 

 shells are also in a calcined or earthy state^ but among- them are some species 

 in the ordinary state of petrifactions ; for example, the Gryphaga above men- 

 tioned, and both species of Hippurites. This structure gives them (especially 

 when contrasted with the other shells) the exact appearance of secondary 

 organic remains : and, after all, may not some of them be true secondary 

 fossils, derived mechanically from older strata by the destruction of which the 

 overlying groups were formed? We do not build upon this, and only throw 

 it out as an hypothesis. But it is in some measure sanctioned by the bosses 

 of secondary hippurite-rock which stand out close to the brim of the Gosau 

 basin : and we think it possible that what we have (in our general section 

 No. 2.) described as concretions of blue limestone subordinate to beds of 

 marl, may in point of fact be rolled masses of the neighbouring secondary 

 hippurite-rock*. 



We have now stated all the facts connected with the overlying deposits of 

 Gosau which appear, as far as we are acquainted with them, of any impor- 

 tance to their history ; and after a general review of the whole question, we 

 are compelled to return to our hrst conclusion — that there is nothing in the 

 structure of the beds themselves, in their relations to the surrounding strata, 

 or in their large series of organic remains, to justify us in considering them as 

 exclusively of a secondary period, and still less in placing them with Dr. Boue 

 on the parallel of the lower green-sand. And, on further comparing the several 

 groups with other analogous deposits on the outskirts of the chain (especially 

 as seen in the Arzt and Untersberg sections |), we find that the development 

 of the newer formations, in all the Alpine regions we have described, is in 

 perfect harmony, and that our first hypothesis, so far from being opposed, is 

 confirmed by the direct evidence of natural sections. 



Those who have classed the Gosau deposits with the lower green-sand, have 

 been apparently led to that hypothesis, by the difficulty of explaining their 



* If this conjecture be true, it will account for the absence of Hippurites in the corresponding 

 group (No. 2.) under the Horn on the Abtenau side; for the deposit is there at a considerable 

 distance from the bosses of secondary hippurite.limestones. Our specimens from this limestone 

 are unfortunately very imperfect. Of the two species of Hippurites found in the overlying marls, 

 M. Deshayes considers one as identical with a species in the Pyrenees, described by Picot de la 

 Peyrouse {Description de qticlques Orthoceratites, p. 23.), and figured by him in Plate 5. : 

 the other he considers as an undescribed species, which is found also near Toulon. 



t Plate XXXVI. fig. 6. & 10. 



VOL. III. SECOND SERIES. 3 A 



