On the Structure of the Delta of the Ganges. 335 



by a clayey cement. Argillaceous marl, 20 feet in thickness, 

 follows the sandstone, terminating at the depth of 150 feet, 

 when it passes into an arenaceous clay intermixed with 

 waterworn nodules of hydrated oxide of iron, from which 

 metallic iron was procured by Mr. J. Prinsep. Weathered 

 mica slate is found attached to the clay of this bed, and 

 throughout the entire range of strata penetrated, scales of 

 mica have always been abundantly met with. At 175 feet a 

 coarse friable quartzose conglomerate occurs, composed of 

 pebbles of different sizes, though none are very large, ce- 

 mented together by clay. At 177 feet, this conglomerate 

 becomes smaller grained, and at 183 feet 3 inches, it is found 

 to pass into indurated ferruginous clay, which continues with 

 but little variation to a depth of 205 feet. Here another 

 layer of sandstone, soft in its upper portion, but becoming 

 more indurated, and assuming the lamellar structure as it is 

 passed through, occurs ; the thickness being however no more 

 than 3 feet. Ferruginous sand with thin beds of calcareous 

 and arenaceous clay prevail from 208 feet to 380. Kankar, 

 with minute waterworn fragments of quartz, felspar, granite, 

 and other indications of debris from primary rocks, are met 

 with in the lower parts of this sandy deposit, where also are 

 found those fossil bones which have given to these boring 

 operations so much additional interest and importance.* 



The first of these relics, Plate ix. fig. 1, a small bone, was 

 brought up from the depth of 350 feet, filled interiorly, and in- 

 crusted exteriorly with the micaceous sand in which it was im- 

 bedded. The bone, of which a full size sketch is annexed, was 

 considered by Mr. J. Prinsep to be the lower half of a hume- 

 rus of some small animal like a dog, resembling the drawing 

 of the corresponding bone of the hyaena in Cuvier, but entire 

 identification was then impracticable^ from the want of ske- 

 letons for comparison. " The bone," says the same gentle- 



* Vide PL ix. fig. 1. a. b. c. 



