Jurassic Mollusca from Arabia. 5 



included in liis division of the " Oliidamu Beds." The same 

 author states that Professor Victor Ulilig agrees with this 

 correlation, besides thinking it probable that the Chidamu 

 Beds are Kimeridgian *. 



It should also be mentioned here that Professor Uhlig is 

 now engaged in examining and reporting upon "The Fauna 

 of the Spiti Shales," descriptions of the Ammonite species 

 having already been published ; and we await with interest 

 the completion of that work, which should finally settle all 

 disputes as to the stratigraphical values of those northern 

 Indian deposits. 



Age of the Arabian Mollusca. — In considering the geolo- 

 gical age of Major Hazelgrove's fossils from Arabia it would 

 seem that there is every evidence to prove that they belong 

 to a higher horizon than tiie Bathonian. The Parallelodon 

 egei-tonianus, as previously mentioned, shows some similarity 

 with a Kimeridgian form from German East Africa. Tiien, 

 again, the Nucula cuneifor7nis, which is characteristic of 

 Indian Jurassic deposits, exhibits besides some marked 

 affinities with Quenstedt's N. ornati, occurring in the Ox- 

 fordian of Germany and England, The iYenVi(ca-cast also 

 appears to possess certain characters which would connect it 

 with the Corallian period. From such comparisons it is 

 reasonable to assume that this fauna should be recognized as 

 originatino- somewhere between the Oxfordian and Kime- 

 ridgian, in which case the Corallian (or Sequanian) would 

 represent its rightful period in the Jurassic series. 



Every detail of research made in connection with the 

 present enquiry tends to indicate that these Arabian lime- 

 stones may be correlated with the Jurassic rocks of Bihin and 

 probably other districts of Eastern Africa, as well as with 

 those occurring on the Tibetan side of the Himalayas — the 

 Niti Pass neighbourhood north of Kumaun and the Spiti 

 district N.N.E. of Simla — and with certain rocks in the 

 Cutch province of Western India. Simihir Jurassic regions 

 are also known in Persia, Baluchistan, and Madagascar. 



Desceiption of the Species. 



Pelecypoda. 



Genus Parallelodon, Meek and Worthen. 



Parallelodon egertonianus, Stoliczka. (PI. I. figs, l-i.) 



Area, J. D. Herbert, Gleanings in Science, 1831, vol. iii. pi. xvii. fig-. 6, 

 p. 272. 



* These opinion? are reproduced and adopted in Professor A. de 



Lapparent's ' Traitt? de Geologie,' lOOG, edition o, p. 1255. 



