NOTE ON SOME POST-PLIOCENE MOLLUSCS FROM THE BYCULLA FLATS. 187 



Bombay Branch of the Royal Asiatic Society.* There was much in 

 it that was interesting and valuable. But this theory was certainly 

 wrong. By a curious coincidence, 1 happened only t)ie other day to 

 pick up near the race-course this specimen, No. 5, which shows, I think, 

 how the theory of the mangrove roots may have originated. You see 

 here is a bit of the root end of some plant firmly embedded in a fragment 

 of tube. Jt may either have grown up naturally through the tube, which 

 had accidentally fallen and become embedded in the earth in such 

 a position as to allow of this, or it may have been poked in to clear the 

 tube by some inquisitive cooly five minutes before I found it. I incline 

 myself to the former theory, both as the more interesting, and 

 because when I first found the specimen, it was completely filled up 

 to the edge at both ends with earth, some of which has since been 

 shaken out, which would hardly have been the case had the piece of 

 stick been pushed in for the purpose of cleaning out the earth. f 

 But however it got there, there is the piece of the plant in the piece 

 of the tube, and it is not impossible that a hasty observer might jump 

 to the conclusion that the latter was deposited round the former in the 

 manner suggested by the author of the work to which I have referred. 

 The general objection to the theory is that the fragments of calcareous 

 tubes are always single, whereas the roots and stems of mangroves 

 are always branching. In this special instance the space between 

 the shell and the wood, now filled up with earth, shows that the 

 former can never have been deposited on the latter. 



But after thus disposing of the theory of another, it is only fair that 

 I should give him a chance by advancing one of my own. My 

 theory is that many (I admit not all) of the shelly tubes found on the 

 Byculla Flats are fragments of the tubes of an interesting and hitherto 

 rare mollusc, belonging to the family of Pholadida?, and variously 

 known as Kuphus, or Septaria, or Furcella aretiaria, or Teredo 



* Since this paper was read, I have fennel a paper by Dr. Buist on the geology of Bombay 



" of the 10th volume of " Transactions of the Bomba 



-uv, >,..u, ,'se suggest ion is here mude, viz., that these tubes are Uo i^ota m luimgsu 



by marine worms through mangrove roots which hava been formed by the infiltration of 



av yago ioi ui me luca volume or " transactions oi tue Doinoay uwograpnicax society. 

 The converse suggestion is here m;ide, viz., that these tubes are the casts of Korings made 

 by marine worms through mangrove roots which hava been formed by the infiltration of 

 lime held in suspension by rain-water, and deposited in successive layers each monsoon 

 within the outer circumference of the original boring. This theory seems to me as unten- 

 able as the other, and formed only for the purpose of accounting for the concentric struc- 

 ture of most at least of the thicker tubes. In the first place, though the fragments of tubes 

 are literally innumerable. I have never yet found one sticking in a piece of wood. In the second 

 place, if the rain-water filtering through the soil of the Byculla Flats were so strongly charged 

 with lime, we should expect to find everything in it thickly coated with lira", not merely 

 the inner surfaces of these tubes On the other hand, the concentric structure of the tube 

 seems capable of explanation by the act of the animal itself in thickening the tube 

 inwards at intervals, for the purpose of reducing the size of the orifice as it diminished in 

 size itself, in the manner pointed out by Sir Everard Home in his paper mentioned 

 below. 



t At the time of reading the stick was pulled out, and found to have been roughly cut 

 to a point, thus establishing the truth of the cooly theory. 



