164 J. Starkie Gardner — Teredo in the Eocene. 



fragments on being released from the matrix." I find no record of 

 Teredo from the Hempstead beds. 



I have never met with any Teredo-bored wood in the Antrim and 

 other northern Eocenes, nor at Bovey Tracey. Additional informa- 

 tion would be of importance, especially with regard to the London 

 Basin, where the tubes often remain as hard cores of pyrites, when 

 the wood itself is soft and perishing. They are rounded and blunt 

 and closed at the thick end and open at the thinner end, and in this 

 state are often mistaken for plant-remains such as roots or stems. 

 On one occasion I was sent for to Bournemouth on account of the 

 supposed discovery of fossil canes or reeds in situ, these being 

 nothing more than casts of Teredo-boring in a vertical position. 



With regard to the habits of the living Teredo, it was, I believe, 

 for a long time assumed to be a purely marine mollusc, and its oc- 

 currence in Eocene deposits that were quite obviously of fresh-water 

 origin was a serious stumbling-block. It has gradually been ascer- 

 tained, however, to ascend very far up tidal rivers ; but whether it 

 ever passes up completely beyond the influence of saline water, is 

 a question that appears to be unsettled. It is one, however, which 

 must be set at rest, if we are ever to understand, and be in a position 

 to restore, the physiography of the great river to which the deposi- 

 tion of the entire English Eocene basin is due. 



The late Dr. Gwyn-Jeffreys appears to have collected more infor- 

 mation bearing on this point than any previous writer, and the 

 following is an extract from his British Conchology, p. 147 : — 



" T. Senegalensis, de Blainv., was discovered by Adanson in the 

 roots of the Mangrove and another kind of tree lining the banks of 

 the Niger, Gambier, and other rivers on the W. coast of Africa, 

 which were only subject to an influx of sea-water for a few months 

 in the year. According to Adanson, the water of these rivers is 

 quite fresh or sweet during the remaining months ; and T. Sene- 

 galensis not only exists, but retains its full vigour throughout the 

 whole year. This statement, however, must be received with some 

 qualification. I was assured by Dr. Welwitsch, the great botanical 

 traveller, that in the tidal rivers of South Africa, the water in the 

 middle stream is fresh, while that of the sides is brackish, and that 

 no kind of Mangrove has been known to live in fresh water. 

 Another sort of ship-worm (Nausitora Dunlopei of Perceval Wright) 

 has lately been found in India, inhabiting the river Comer, one of 

 the branches of the Ganges, and a perfectly freshwater stream, that 

 joins the main river at a distance of about 70 miles from the 

 sea. Dr. Kirk, the friend and companion of Livingstone, informs 

 me that he picked up a piece of ebony (Dalbergia melanoxylon) on a 

 sandbank in the Zambesi river, the water of which was there always 

 fresh and drinkable 100 miles from the sea — very far beyond the 

 influence of the tide, which never comes more than 10 miles up the 

 creeks of the delta. This piece of ebony was pierced in all direc- 

 tions by a species of Teredo having a calcareous sheath. The kind 

 of wood mentioned by Dr. Kirk resembles the ebony of commerce, 

 but is utterly worthless except as fire-wood ; and therefore it is not 



