1854.] LOFTUS — TURKO-PERSIAN FRONTIER. 467 



Amongst the fossils from the bed No. 6 are : — 



Nummulites Biaritzensis. Pecten. 



Orbitoides dispansus. Ostrea, 4 smooth species. 



Operculina granulosa .' , 1 plicated. 



Alveolina subpyrenaica. , 1 vulselliform. 



Several undetermined Zoophytes. Anemia. 



Clionites, 2 sp. Nerita, 2 sp. 



Spines of Cidaris. Natica, 2 sp. 



Echinus. Turbo .' 



Temnopleurus. Trochus ? 



Teredo, in wood .' 2 sp. Ceiithium ? 



Corbula. Purpura. 



Tellina. Pleurotoma, 3 sp. 



Corbis ? Fusus. 



Lucina. Pyrula. 



Venus. Rostellaria. 



Cardium, 2 sp. Strombus, 3 sp. 



Cardita. Voluta, 2 sp. 



Isocardia ? Seraphs. 



Area. Cyprsea, 3 sp. 



Pectunculus. Oliva. 



Nucula. Pileopsis. 



Chama. Nautilus. 



Modiola. Crustacean remains. 



Mytilus, 2 sp. Teeth of Shark. 



Perna. Gyrodus. 



Spondylus. 



The nummuhtic rocks, like all the rest of the rocks of the range, 

 are greatly disturbed. They rise from beneath the beds of the 

 gypsum formation in elongated saddles of compact crystalline lime- 

 stone, running parallel to each other, and having a qua-quaversal 

 dip. Frequently, when much elevating force has been exerted, huge 

 masses of the limestone stand isolated, with lofty precipices on all 

 sides, bearing on their summits acres of pasturage and springs of 

 delicious water, to which the native chiefs and their adherents can 

 retire in safety, and, with a handful of men, defy the whole power of 

 the Persian Government. 



Mr. Loftus describes in detail the altered conditions of much of 

 this series, and explains the great clefts or "Tangs" (as they are 

 termed in Persian) which pass through the elongated limestone 

 saddles. These tangs are very numerous, and are the most peculiar 

 feature of the nummulitic rocks. All the great rivers which fall into 

 the Tigris from the east rise in the interior of the Zagros ; and, as 

 their course is generally from north to south, they cross the ridges 

 of the great chain diagonally. The manner in which this effected 

 is very remarkable. Instead of flowing in a S.E. direction along the 

 trough which separates two parallel limestone saddles, and by this 

 means working out their channel in the soft rocks of the gypsiferous 

 series, or of the alluvium, and afterwards rounding the end of the 

 saddle, at the point where the extremity of its visible axis dips under 

 the overlying deposits, each of these rivers takes a direction at right 

 angles to its former course, and passes directly through the limestone 

 range by means of a " Tang." On reaching the next parallel gypsum 



