Chap. VIII. ] arrialoor group — trichinopoly district. 141 



It will have been observed in the foregoing descriptions that of this upper belt of fossi- 

 liferous rocks, nothing is seen anywhere in the neighbourhood 

 of the Coleroon, and indeed up to the watershed of the district, 

 the Cuddalore group rests upon the unfossiliferous band I have described above. In the 

 nullah near Authicoodicaud, (a village near the boundary of the Cuddalore beds, 3 miles North 

 of the Arrialoor and Wodiarpolliam road,) we first meet with the fossiliferous beds of the 

 upper zone. The beds are grey and ochreous shales, sometimes calcareous, and containing 

 a species of oyster in considerable abundance. Two miles farther North similar calcareous 

 Fossiliferous bed at Saia shales are met with in a little nullah to the East of Sainthoray, 

 *^^°^'^y- about half way between that place and Vellapencoorchy. The 



countiy is here covered with red soil and a low jungle, and the beds are only seen in the nullah 

 which cuts into them to a depth of 5 or 6 feet. At this place fossils are tolerably abundant, 

 and they comprise a number of species not previously noticed. The most striking are 

 Nautihis Danicus, Schloth., and a large thick bivalve, probably a Crassatella, fragments 

 of which are abundantly strewn around. There are also several smaller shells, Nalicce 

 Arete, Turritellce, &c., most or all of them apparently distinct from those of the lower 

 zone ; and an Ovulum. 



Again a mile further North, in the upper part of the nullah that runs past Ninnyoor, the 



same band is exposed, and more extensively, while the fossils 



At Ninnyoor. , . , 



are far more numerous and various than at either of the locali- 

 ties previously noticed. Nautilus Danicus and the Crassatella here also predominate, 

 imbedded in a loose calcareous shale. No Ammonites are associated with them, and the 

 characteristic Mesozoic genera, Inoceramus, Eadiolites, Trigonia, Pleurotomaria and Opis, 

 all of which are common in the lower zone, and some of them particularly abundant, are 

 equally wanting in the Ninnyoor beds. Nerincea indeed is the only characteristic Mesozoic 

 molluscan genus which links the fauna with that of Cretaceous times, while the general 

 aspect of the fauna reminds us more of that of Nummulitic or at least Tertiary times, in the 

 association of Valuta, Fusus, Ovulum, Turritella, Natica, Trochus, Solarium, Chemnitzia, 

 Pyramidella, Modiola, Cardium, Cardita, Crassatella, Corbula, Coj-bis, Lucina, Venus and 



Resemblance of fossils to Cytherea. There is much resemblance between some of the 

 those of Eajamundry. species and those of the Eajamundry beds, the fossils of which 



have been described by the Eeverend S. Hislop, and one species of Turritella appears to be 

 identical with T. prcelonga of that formation. An Echinid occurs, but distinct generically 

 (Catopygus) from those of the lower beds, and some corals, the affinities of which I have 

 not determined. 



It will be seen from the above, that the Tertiary aspect of the fossils of the Ninnyoor bed 



is more due to the absence of characteristic Cretaceous forms 

 Age of upper zone. 



than to the presence of those which we have been accustomed to 



regard as peculiar to Tertiary deposits ; but the latter are not entirely wanting. Eegarding 



these facts alone, it is difficult to avoid the conclusion, that in these beds we have deposits at 



least as recent as the MEEStricht and Faxoe beds of "Western Europe. But, on the other hand, 



v/e shall see in our review of the Pondicherry area, that we there find Nautilus Danicus, 



Ovulum and Oliva, apparently associated with Nautilus Bouchardianiis, an Ammonite, a 



Humite, Ostrea tegulanea, Ostrea stomatoidea, and a number of other fossils of the lower 



zone, and above all v/ith Turritella monilifera, a fossil which in Trichinopoly does not range 



