TERTIARY SYSTEM. 



87 



" The smaller of the ' regular ' echinoids is a Cyphosoma, but cannot he specifically 

 determined." 



Mr. Tipper refers the ammonites to the genus Hoplites. A 

 small fragment of Scaphites sp. and a brachiopod very closely allied to, 

 if not identical with, Terebratula semiglobosa d'Orb., also occur at the 

 same horizon. The limestone overlying these beds is full of lamelli- 

 branchs, among which the genus Exogyra is very common and led Mr. 

 Griesbach to call the rock " Exogyra limestone." Gryphaa vesi- 

 culates Lam. occurs in this limestone at about 150 feet above the 

 horizon of the ammonites ; a little lower down, the same rock has also 

 yielded hippurites and Pecten {Neithea) quinquecostata Sow. The 

 limestones, therefore, are perhaps not older than senonian, whilst 

 the underlying marls may be as old as cenomanian. 



Tertiary System 



In Saighan and Kahmard, the limestone with Gryphcea vesicularis 

 is overlain by a fine-grained bluish-grey concretionary sandstone, 

 which is locally replaced by either clunchy shale or pale-grey 

 calcareous shale followed by gypsum ; above this is another bed of grey 

 shale sometimes containing small veins and nodules of sulphur. Above 

 this again are grey, brown or red shales. After this there is usually a 

 pronounced unconformity, above which are beds of bright red 

 conglomerate. 



I have followed Mr. Griesbach in classing the whole of this series as 

 Tertiary, although the boundary assumed between it and the un- 

 doubtedly Cretaceous limestone is merely a lithological one and has not 

 been fixed from palseontological data; throughout Saighan and 

 Kahmard, the horizon marked at one point by a concretionary sandstone 

 and at another by a clunchy shale is undoubtedly the natural line to 

 take as the base of the series. It will probably be necessary eventually 

 to give this system a local name, but as its characters are decidedly 

 variable, it seems preferable to risk a certain amount of inaccuracy and 

 continue to call it Tertiary provisionally rather than to saddle it with a 

 name which subsequent work may prove to be unsuitable. 



