﻿185 1.] 



SALTER ON SILURIAN FISH REMAINS. 



263 



May 28, 1851. 

 The following communications were read : — 



1. On the Geological Structure of the Mountain Range of 

 Western Persia. By William Kennett Loftus, Esq., F.G.S. 



[In a letter to J. S. Bowerbank, Esq., F.G.S.] 



Few mountain-regions, perhaps, exhibit such uniformity of structure 

 as the Tagros Range. Here the direction of the great chains is gene- 

 rally from south-east to north-west, the Tagros consisting entirely of 

 a succession of limestone saddles which extend in parallel lines for 

 many miles, the troughs between being filled with much-contorted 

 beds of gypsum and variegated marls. No fossils whatever are found 

 in these gypsum-beds, but in the limestone are sparingly scattered 

 Ostrcece, Buccina, Nummulites, and Echini, of tertiary forms, as far as 

 I am able to judge ; but the rock is so crystalline that it is impossible 

 to procure a single specimen exhibiting any decided character. The 

 beds below the limestone are red chert-conglomerates, sandstones, 

 and blue shales. At Khorramabad the Yaftah Kuh rises abruptly 

 from the plain and consists of grey cherty limestone, abounding with 

 thick beds of flint, which I am inclined to believe belong to the 

 Chalk-formation, although fossils are entirely wanting. On the eastern 

 side of the Tagros, as far as the base of the Kuh Elwend, the serrated 

 peaks, which rise from these high table-lands and form picturesque, 

 although by no means magnificent scenery, are of hard, compact, and 

 crystalline blue limestone, containing a few of the same fossils as 

 before. This rests unconformably on beds of yellow slaty limestone, 

 which again rest upon clay -slates. At Kuh Elwend these clay-slates 

 are raised into a vertical position by felspathic granite, which consti- 

 tutes the axis of the chain. Beds of mica-schist are also found in 

 conjunction with the clay-slates. From Hamadan to Isfahan the 

 order is as follows (descending) : — 1. blue limestone, much contorted ; 



2. yellow calcareous slates; and 3. clay-slates. 



2. On the Remains of Fish in the Silurian Rocks of Great 

 Britain. By John William Salter, Esq., F.G.S. 



A belief in the existence of Fish-remains in the older members of 

 the Silurian system, as well as in newer deposits of that period, has 

 of late years grown prevalent in this country, and has attracted con- 

 siderable attention. The statements put forward in the session of 

 1846-7 by two of our leading geologists as to these remains having 

 positively been found in these lower strata, by Professor Sedgwick in 

 South Wales, and by the collectors of the Geological Survey in North 

 Wales, added to the fact of Professor M'Coy having previously de- 

 scribed a fish-scale from the Silurian rocks of Waterford, appear to 

 give a sufficient basis for this opinion. It has now assumed a definite 



