274 THE FOSSIL ECHINOIDEA 



The result of the examination and description of the Fossil Corals of the Gaj 

 series* proved that it was on a higher horizon than the Nari series, and this has been 

 confirmed by the study of the Echinoidea which we now offer to palaeontologists. 



In fact the deductions made by the geological surveyors in the field have been 

 proved to be correct. The evidence which was obtained from the study of the Corals 

 is confirmed by the examination of the Echinoidea, and indeed it may be said that 

 although the Corals distinctly gave a Miocene horizon to the Gaj series, it was not a 

 high one. Nevertheless the Echinoidea are indicative of a high horizon in the 

 Miocene. 



The following abstract of the description of the Gaj series from the ' Manual of 

 the Geology of India,' pp. 463 et seq., will be found useful : — 



" Gdj Group. — Upon the Nari group, almost throughout Sind, there is found 

 resting a mass of highly fossiliferous limestones and calcareous beds, usually more or 

 less shaly, always distinctly stratified, and easily distinguished from the limestones of 

 the older Tertiary formations by the absence of Nummulites. A superb section of the 

 strata forming this group is exposed on the banks of the Gaj river, the only stream 

 which cuts its way through the Khirthar range, and in the neighbourhood of which, 

 west of the range, the fine section of Lower Tertiary and Cretaceous beds, akeady 

 noticed, is exposed. From this river the present group derives its name. 



" On the eastern flanks of the Khirthar range, in Upper Sind, the Gaj group 

 forms a conspicuous ridge, the hard dark-brown limestone bands near the base of the 

 formation resisting the action of denudation far more than the soft sandstones of the Nari 

 beds, and rising every here and there into peaks of 1000 and 1500 feet, or even more, 

 escarped to the westward, and sloping to the east, Amru (the highest summit of the 

 Gaj ridge) being 2700 feet above the sea. Still the limestone bands, although so 

 conspicuous, are subordinate, the greater part of the group consisting of sandy shales, 

 clays with gypsum, and, towards the base, sandstones. Many of the bands of limestones 

 appear very constant in position, and may be traced for a long distance. As a rule 

 they are dark brown in colour ; but one bed is white, and abounds in corals and small 

 Foraminifera (Orbitoides), whilst some of the darker bands contain Echinodermata in 

 large quantities. The uppermost portion of the group is usually argillaceous, being 

 chiefly composed of red and olive clays with gypsum ; and these beds pass gradually 

 into precisely similar strata belonging to the overlying Manchhar group. The passage- 

 beds contain, amongst other fossils, Turritella angulata, and forms of Ostrea and Placuna, 

 and the following : — 



Corbula trigonalis. Tellina suhdonacialis. 



Ludna [Diplodonta) incerta. Area LarJcanensiB. 



" All of these have allies living in estuaries at the present day. Area granosa, a 

 recent representative of A. Larhanends, being one of the commonest and most typical 

 of Indian estuarine Mollusca, To these estuarine passage-beds further reference will 

 be made presently, when the relations of the Manchhar to the Gaj beds are discussed. 



* Pal. Indiea, Series XIV. vol. 1 (now 2), 1880. Sind Fossil Corals and Aloyonaria, P. Martin Duncan. 



