194 Proceedings of the British Association for [Sept. 



conducted him ; and expressed his conviction that strata 

 might, in ^,11 cases, be identified by means of the remains 

 of fishes ; or, in other words, that each geological epoch 

 was characterized by its peculiar and exclusively appropriate 

 race of fishes. 



During this part of the proceedings Mr. Sedgwick took 

 the -opportunity of putting M. Agassiz's knowledge to a 

 severe test. He exhibited a specimen containing impres- 

 sions of fossil fishes, and M. Agassiz, after explaining the 

 zoological characters which distinguish the fishes of diffe- 

 rent geological epochs, at once declared the specimens before 

 him had been derived from the new red sand-stone. 



8. Dr. Trail then read a paper on the Geology of Spain. 

 He confined his remarks chiefly to the province of Anda- 

 lusia. In this interesting country we have every variety 

 of rock, from the oldest primary, up to the tertiary strata. 

 The mica slate of Andalusia contains many interesting 

 minerals, as iron,, glance, and lead ore. This last mineral 

 is so abundant that no less than 35,600 tons were ex- 

 tracted in one year. The primary rocks are succeeded by 

 secondary sand-stones, in whose fissures interesting osseous 

 remains occur. These lime-stones extend to the opposite 

 coasts of Africa. This lime-stone is followed by new red 

 sand-stone, and gypsum marl, abounding in salt and saline 

 springs. Oolite rocks occur near the ancient town of 

 Cartua; and chalk, with flints, is observed at Labriga. 

 Tertiary and fresh water lime-stones also occur, as has been 

 noticed by Colonel Silvertop. 



The beds at Valencias vary from 6 to 8 feet in thickness, 

 and repose on^marl and gypsum. 



Friday, \4:th August. — 9. Mr. Phillips gave an account 

 of a small portion of a tertiary formation which had been 

 observed in Yorkshire. 



10. Messrs. Murchisonand Sedgwick then gave an account 

 of the rocks anterior to the coal, and posterior to the primary 

 strata. These rocks, which were formerly distinguished by 

 the absurd term of transition strata, have been, unaccount- 

 ably much neglected by geologists ; and, unfortunately, the 

 use of this term has given rise to much confusion in geolo- 

 gical writings. Mr. Murchison has, for several years, 

 devoted his time to the study of the older secondary rocks. 



