584 



NA TURE 



[April 21, 1898 



crater walls of the Fondi di Baia, Lago d'Averno, and 

 the two outer crater rings of the Cratere di Campana, 



fragmentary materials. In fact, there seems little reason 

 to doubt their origin as segments of volcanic crater walls. 



Fig. 2. — CapD Miseno from the Northern side of Porto .Miseiio. 



have been partially obliterated by outbursts from other I Passing now from the hills which bear a more perfect 



volcanic vents on or near their periphery. I resemblance to a typical crater wall to those in which 



In all these cases of partially destroyed crater walls, | the resemblance is less perfect, I have been led to adopt 



Table showing supposed Chronological Order of Formation of Volcanoes of Phlegil«an Fields. 



7. Monte Nuovo. 

 (I =138). 



4, 5. Fondi di Baia. 



6 Baia. 



1. Capo Miseno.^ 

 3. Bacoli. 



2. Porto Miseno. 



Fossa Lupara \ 



I 

 Middle ring \ 13. Cratere di Campana. 



i . 

 Fossa Schianataj 



17. Cigliano. 



12. Montagna Spaccata 



8. Averao. 



II. Canipi^lione- 

 10. Cuma. 9. Grille- Rosso. 



a. Monte di Procida. b. M. Salvatichi. 



c. Ruscello. 



14. Solfatara. 26. Nisida. 



25. Santa Tere 



19. Pianiua. 22. Chiaja. 23. Fuurigrotta. 24. San Str; 



20, Soccavo. 21. Naples. 



18. Quarto. 



their shape on the whole agrees very well with tliat of 

 the five perfect crater walls enumerated above, and with 

 the generalised type of a volcanic cone composed of 



NO. i486, VOL. 57] 



d. Monte Sau Sevprino. 



the following criteria as indications : firsth', of whether a 

 hill can be regarded as a segment of a volcanic crater wall 

 or not; and, secondly, of the position of the volcanic crater. 



