INTEODTJOTION. 



It may be safely presumed that the few species described in the following 

 pages do not represent the complete fauna of the neocomian in Baluchistan, 

 and it must also be admitted that this fauna is really poor in number of species. 

 The collection which I examined consists almost exclusively of belemnites, but they 

 appear in countless numbers, and the strata in which they occur have accordingly 

 received the name of the belemnite shales. I would have refrained from describing 

 so small a number of species, and I should have considered it better to await the 

 collection of more material, but it appeared advisable to arrive at some definite 

 knowledge of the fauna of the mesozoic rocks in Baluchistdn. 



It was of course a fact of considerable interest that beds of neocomian age 

 should be found between the Jurassic Polyphemus limestone and those strata which 

 represent the top of the cretaceous formation, while apparently the whole of the 

 middle and the greater part of the upper cretaceous formations, from the barremien 

 up to the lower aturien, were missing in Baluchistdn. I do not wish by any means 

 to say that these stages are not represented there, — in fact there is reason to believe 

 that they are developed in parts hitherto unsurveyed. 



The fauna afforded a double interest when it was discovered, that except one 

 species of pelecypod, which was new, the remainder could be identified with well 

 known neocomian belemnites. These are : 



Belemnites subfusiformis, Easpail. 



Belemnites latus, Blainville. 



Belemnites dilatatm, Blainville. 



Belemnites pistiliformis, Raspail. 

 Small as the number may be, it is quite sufficient to fix with the greatest accuracy 

 the age of the belemnite shales, which must now be considered to be of neocomian 

 age, and most probably they represent the etage hauterivien of the French geologists. 



I.— PELECYPODA. 

 Order: ANISOMYARIA. 



Family : OSTREIB^ 



Genus : GRTPH^A, Lam. 



Gryphjsa oldhami, spec, nov., plate I, figs. 1-le, 2-26, 3-36. 



This pretty little species hardly ever grows longer than 30mm., its width vary- 



ing somewhat between 20 and 22mm. The left valve, which is much larger than the 



right one, is narrow, somewhat triangular in shape, and strongly inflated, generally 



dropping steeply in both the anterior and posterior directions; the posterior side is 



