Chap. X.] valudayur and arrialoor groups — pondicherry. 159 



regularly to the North-east, and near the Madras road it appears at 



the surface, and is quarried by the natives. At this place it is a bluelsh 



limestone, in color not unlike the nodules of the " Valudayur" beds, 



but the fossils Ostrea tegulanea, Gryphoea orientalis, and others equally 



characteristic, would be sufficient, even in the absence of stratigraphic 



evidence, to prove its Arrialoor age. Besides these fossils, vrhich are 



here very abundant though difficult to extract entire, a species oi Pinna 



is very common, and I obtained one specimen of a large annulated 



Hamite (H. Indicus ? ). 



At WattampoUium again it is exposed in a little nullah. Area 



Pondicherriensis or Japetica ? the small Area 

 At WattampoUium. 



(A. Gamana ?) so commo;i at Verdoor, Gryphoea 



orientalis, and Ostrea tegulanea and Fungia filamentosa are here com- 

 mon. An Opis, of a peculiar form, also occurs, which I have not met 

 elsewhere. 



Again, half a mile to the North-east, the same bed appears in the 

 At Koyapoothoopak- ^^^g^ tank at Koyapoothoopakkum, and a small 

 ^^™' excavated tank in the village is paved at the sides 



with blocks of limestone principally derived from this bed. These are 

 full of fossils, and being somewhat decomposed, are easily broken up, 

 affording one of the best fossil grounds in the district. The most com- 

 mon species is the smooth Area (A. Gamana?) of which some blocks 

 are almost entirely composed ; the valves being generally united. I 

 have obtained also specimens of Nautilus Bouchardianus, Ovulum, 

 Natica, a large Panopcea, and several shark's teeth, principally of 

 species of Lamna, also from the same locality. Ammonites Indra, 

 Forbes. 



Beyond Eoyapoothoopakkum the bed may be traced for some miles 

 by the usual indications of scattered fragments, though nothing is seen 

 in place, and at length in the waste channel at the East corner of B,y- 

 proempakkum tank, the out-crop is seen for the last time dipping to the 



