290 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



of a black siliceous substance, giving out a remarkably strong 

 odour of bitumen, when struck. 

 3. Highly crystalline, blue, fcetid limestone. 



At the Pass between the plains of Ser A'b i Sir and Faylaiin (Sec- 

 tion, fig. 12), the blue limestone, 5, is much contorted, and sur- 

 rounded by the yellow, 4, which appears to be conformably deposited 

 upon it. 



In this neighbourhood the yellow limestone constitutes the sum- 

 mits of many isolated tabular forts, and rests on a base of blue lime- 

 stone. The notorious Kalah Seffeed is a fine example of this. 



IV. Paleozoic Rocks. 



The only instance in which undoubted deposits of this age were 

 observed by me was on the east side of the Kuh i Kellar range, be- 

 tween Naughiin and the plain of Cheraghiir, in the heart of the 

 Bakhtiyari Mountains. This range is composed of the ambiguous, 

 altered, blue limestone ; but I had only an opportunity of examining 

 an insignificant portion of it, overlooking the plain of Cheraghur, 

 where I gained no information whatever. Just before entering the 

 plain from the west, however, I stumbled upon two or three blocks 

 of highly crystalline grey limestone, weathering rusty-yellow, filled 

 with a species of Orthis, which Mr. J. Morris considers as a form 

 intermediate between the Devonian and Silurian species. 



Want of time during a hasty journey prevented my giving the 

 locality the attention it deserved ; but I was informed by the natives 

 that at the summit of the range are great quantities of similar fossils. 



With the Orthis are associated a small Nucula and a few other 

 indistinct fossil forms. 



V. Metamorphic Schists. 



In the more disturbed portions of the blue limestone we have 

 nothing whatever to guide us in determining the age of the under- 

 lying rocks. 



At Senna in A'rdelan, the Kiih i A'b i Der, which overlooks the 

 town on the S.W., is composed of an alternating series of blue lime- 

 stones, — dark-yellow, arenaceous, and calcareous slates, exceedingly 

 hard, compact, and sonorous, — and dark-blue schists. These rocks 

 pass into each other insensibly, — are so utterly devoid of fossil con- 

 tents, — and are so completely isolated, by the intervention of the 

 granitic chain of Merwari, from the less complicated blue limestone 

 masses on the West, — as to leave us in utter ignorance of their true 

 age. 



Between Bisutun and Essadabad (see fig. 1, e, p. 326), as well as 

 in several localities between Hamadan and Isfahan, the blue lime- 

 stone rests unconformably on yellow calcareous slates. 



In immediate juxtaposition with the igneous rocks are vast de- 

 posits of dark-blue, indurated, calcareous, and fissile clay-slates, 

 which extend on the west of Kiih Elwend from the district of 

 Feridun, in the Bakhtiyari, through the plains of Biirujird and 



