ON THE ORIGIN OF MONTE NUOVO. 19 



Crinoids. Some species, but not all, have, besides the three already 

 mentioned, a fourth orifice in the cup, which M. von Buch has de- 

 scribed as the ovarial orifice. 



The Cystidea may be separated into two groups : — 



1. Those in which the cup exhibits marks of radiated structure — 

 Hemiscosmites, Caryocystites, Echino-encrinites^ and Cryptocrinites. 



2. Those in whose cup all trace of radiation is lost, e.g. the SphcB- 

 ronites. These may be arranged into the genera Echinosphcerites , 

 Sphceronites, and Protocrinites. 



The author then proceeds to describe the Russian species of the 

 latter group. He states generally with regard to thenij that their 

 name is derived from the usually spherical form of the cup, and that 

 they exhibit distinctly the characteristics of the Cystidea, in the pro- 

 jection of the dorsal part of the cup and the existence of an ovarial 

 orifice. Gyllenhal was the first to recognise the organic origin of 

 the cup, which had before been thought to belong to the mineral 

 kingdom, and he spoke of them as Echinoderms. Hisinger and 

 Von Buch afterwards recognized the proper systematic position of 

 the Sphasronites among the Crinoids. 



List of Russian species. 



1. Echinosphaerites aurantium, Gyllenhal and Wahlenberg. 



2. E. aranea, Schlotheim 



3. E. poraum, Gyll. and Wahl. 



4. Sphaeronites Leuchtenbergi, Volborth. 



5. Protocrinites oviformis, Eichwald. 



[D. T. Ansted.] 



On the Origin of Monte Nuovo, m a letter from an eye-witness of 

 the eruption in 1538. 



The history of the formation of Monte Nuovo on the shore of the 

 Bay of Naples near Pozzuoli, in 1538, has latterly been a subject of 

 controversy. It was long held by geologists to have been produced 

 by the accumulation of blocks, scoriae, and ashes ejected from an 

 opening that suddenly took place in the ground near the ancient 

 Lucrine Lake, the loose materials being in part consolidated by con- 

 densed aqueous vapour that issued from the same orifice. This view 

 is maintained by Mr. Lyell, after a personal examination of the spot 

 in 1828, in the first edition of his ' Principles of Geology,' published 

 in 1830, and in the subsequent editions. But in the fourth volume 

 of the ' Memoires pour servir a une Description Geologique de la 

 France,' containing researches by MM. Elie de Beaumont and Du- 

 frenoy, on the Volcanic Countries of the Two Sicilies, compared with 

 those of Central France, published in 1838, M. Dufrenoy, in his me- 

 moir on the Volcanic country around Naples, maintains that the Monte 

 Nuovo was formed by the sudden elevation of previously formed 

 beds of tufa. He states as his opinion, " that the Monte Nuovo rose 

 from the earth in the form of a vast swelling or dome (^ampoule) 



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