Revised Notes on Fossils. 241 



t 



lite. I can't help thinking that these shells are new. At any 

 rate, I can find nothing like them. 



" In the Trichinopoly deposit, there is no sign or trace of a 

 Nautilus, a Baculite, or an Ammonite ; nor can I identify any 

 of the shells obtained from that locality with those found at 

 Seedrapett. In their most marked characteristics, they appear 

 totally distinct, even the Teredo in the wood appears different. 

 That in the Trichinopoly specimens being apparently a nak- 

 ed worm, while those in the specimen from Seedrapett, have 

 a shelly covering. We may safely conclude, therefore, that 

 the formations are totally distinct, and belong to different 

 geological epochs. 



" In the paper marked 11, is a curious substance common 

 at Seedrapett, which are supposed to be a piece of petrified 

 Sponge or Fungus, but this has been doubted." 



Some pieces of the silicified wood, which Dr. Wight at 

 Madras had had cut, and which I examined with a micros- 

 cope, were undoubtedly coniferous. 



Ostrea* trabeculata, J. M. — Both valves bent laterally, and covered with 

 folds with toothed edges like 0. serata, and 0. carinata ; but instead of 

 the folds being rounded as in the first, or presenting narrow sharp 

 ridges as in the second, they present along the ridges hollow grooves ; 

 another remarkable difference is, that in the Indian fossil, the folds 

 instead of radiating from the summit of the valves, and diverging with 

 a lateral curve to the margins, descend straight on either side of an 

 elevated ridge to the margins of the valves like rafters. This species 

 is figured in the Madras Journal of Science, No. 28, July 1840, as 

 Ostrea carinata. 



Although the species is distinct from either of the ostra- 

 cites which characterise the chalk, yet its form is the same ; 

 and this is the more important, as most of the ostrea with 

 folded lunate valves that have been found in Europe, ap- 

 pear to be confined to the chalk formation. This species is 

 generally about three inches long ; but from fragments in 

 the same collection there would appear to be individuals of 

 gigantic dimensions in the Pondicherry rock. 



Nautilus. — Three distinct species of this genus are includ- 

 ed in this collection ; the orifice of all being broken and filled 

 with a hard calcareous deposit, it will be difficult to deter- 



* Figures of these fossils will be given in a future number, provided we can ob- 

 tain correct lithographic drawings of them. 



* 



