F. RUTLEY OX BRECCIATED PORFIDO-ROSSO ANTICO. 161 



small siliceous veins in which minute "horses " of the rock occur; 

 but the specimen from which they were cut is not of the brecciated 

 variety. 



Discussion. 



The President pointed out that some of the antique sculptures 

 of porfido-rosso in Italy show on their polished surfaces clear indi- 

 cations of a brecciated structure. He read the following passage 

 from his journal during his stay in Florence, in December 1875 : 

 — '' In one of the first rooms at the Pitti is a superb vase of 

 porfido-rosso, a sort of saucer in form, about 8 feet across. This 

 certainly is a breccia, being full of pieces angular and subangular, 

 of different grain and crystallization, darker or lighter than the red 

 matrix, also porphyritic, just like what one would expect a highly 

 altered ash to come to, and the crystals had rather the appearance 

 of that." At that time he was familiar with volcanic agglomerates, 

 but not with crushed rocks; but he now thought Mr. Rutley's 

 explanation was probably the right one. 



