Professor Silliman's Mineralogical Notes. 147 



but his own will, and who has shewn in this act that he was 

 unworthy of so noble a subject. 



5. Fish of Mont Bolca. 



At Padua we found the most complete collection of the fossil 

 fish of Mont Bolca, probably in the world ; over 500 speci- 

 mens, generally presenting both sides, some of them five or 

 six feet long, and all remarkably perfect. We visited this 

 celebrated locality last Friday. It is in a very wild and 

 romantic region, surrounded by lofty mountains. Mont 

 Bolca itself is 2000 feet high ; and to the north and east the 

 Tyrolese Alps rise abruptly, leaving a profound and steep 

 valley between them and the base of Bolca. Columnar basalt 

 in regular forms crowns the summit, and intrudes between 

 the vertical fish-beds. 



6. Mineralogical Notes. 



Sacacchite is a silicate of lime and alumina, containing 

 fluorine, and occurs in square prisms highly modified. 



Leucite occurs at Vesuvius in the older ejected blocks, as 

 well as the most recent lavas, and it is observed in some 

 instances undergoing a change to Ryacolite, while still re- 

 taining the external form of leucite, and sometimes cavities 

 of ryacolite crystals are formed in the leucite. 



Zircon occurs at Vesuvius in beautiful white and blue oc- 

 tahedrons in the old ryacolite gangue. Fluor spar occurs in 

 octahedrons with hornblende in the older lavas. 



Forsterite is identical with anorthite. 



Davyne is regarded by Professor Sacacchi as a variety of 



Nepheline. The six-sided prisms are striated longitudi- 

 nally, and are modified by a plane on the terminal edges, 

 and another on the lateral ; it occurs in a compact pyr- 

 oxenite gangue, while the nepheline occurs in a gangue of . 

 ryacolite. 



Arragonite is formed in an old mine at Monte Vasa from 

 day to day, at a temperature below that of boiling water. 



Buratite comes from Oampiglia in the Maremma Pisena 

 in Tuscany, and not from Volterra. 



k2 



