CRETACEOUS STRATA. OF THE LOWER 1ST ARB AD A, REGION. 



153 



of correcting my former determination ; and the species is Ecliino- 

 brissus Goybeti, Cott., from the Cenomanian of the Lebanon. Several 

 fairly well-preserved parts of a Gidaris were collected by Mr. Bose, 

 and one or two belonging to the same species had been collected by 

 Captain Keatinge and placed in the Calcutta Museum. These 

 Mr. Bose considers to belong to Gidaris cenomanensis, Cotteau ; but 

 there are well-marked specific distinctions present, although the 

 narrow ambulacra have four rows of interporiferous granules and 

 the median suture is sunken in the interradia. The excessive size 

 and irregularity of the warty granules beyond the scrobicular 

 circles, and the proximity and large secondaries of these last- 

 mentioned structures, are sufficient to separate the species, and, 

 moreover, the Indian form is a large one. Mr. Bose was quite 

 right in placing the form near to C. cenomansnsis. It has been 

 necessary to establish a new species for the form Cidaris nama- 

 dicus, nob.* 



An Orthopsis was found and recognized by Mr. Bose, and he appears 

 to consider that it is 0. similis, Stol., described from the Arrialur 

 strata of S. India. But there are specific differences ; the Bag 

 form has two of the radial plates not entering the periproctal ring, 

 and the numerous rows of primaries do not extend so far up above 

 the ambitus as in Stoliczka's species. The other supposed specimens 

 of Orthopsis collected by Mr. Bose belong to the genus Cyphosoma. 



It will have been observed that the Argillaceous limestone has 

 a very interesting fauna, and it appears that Nucleolites similis also 

 occurs as a variety, and this species of d'Orbigny brings the beds into 

 relation with the Chloritic Marl of Europe. 



The Echinoidea of the underlying Nodular limestone were next 

 examined, and only two species could be identified from Mr. Bose's 

 collection, and they are common. They are the two Hemiasters, 

 H. cenomanensis and H. similis, the commonest forms in the con- 

 formable marl above. There are no Gault or Albian species present, 

 and there are no stratigraphical data which will permit of the 

 division of the few feet of beds into a Gault or Albian and a 

 Cenomanian. 



The Coralline limestone, which is above and conformable- to the 

 Argillaceous limestone, contains the following species : — Cidaris 

 namadicus, nob., which also occurs in the Argillaceous beds below ; 

 Cyphosoma cenomanense, which has a similar vertical distribution ; 

 Nucleolites similis, var., Hemiaster cenomanensis, and IT. similis : all 

 these are met with in the limestone below, and the two Hemiasters 

 are also found in the Nodular limestone. 



Messrs. Blanford and Wynne, and also Messrs. Medlicott and 

 Blanford, in the ' Geology of India,' considered that the Nodular 

 limestones, the marl, and the Coralline limestones belonged to a con- 

 formable group, with a fauna indicating one Cretaceous horizon, and 

 the examination of the collections of Echinoidea proves that these 

 views are correct. 



The age of the Ostrea-bed at the base of the Nodular limestone 

 * About to be described in the Records of the Greol. Survey of India. 



Q.J.G.S. No. 170. m 



