808 W. Carruthers — Petrified Forest near Cairo. 



scattered over the surface amid rolled and angular fragments of dark 

 grit, pebbles of chert, jasper, and quartz." They are of various 

 lengths and size. The largest linger saw were from 50 to 60 feet long. 

 Similar measurements have been given by Newbold^ and D'Hericourt.^ 

 The specimens are frequently deeply fissured transversely, suggesting, 

 as we have seen, the notion of a jointed stem like a bamboo or calamite. 

 The fissures sometimes pass right through, so as to break up a long 

 stem into numerous fragments, a foot or two in length. Neither 

 branches nor roots are found attached to the stems, nor has any 

 trace of bark been detected. Externally they have a striated, fibrous 

 appearance, as if they had been considerably decayed before being silici- 

 fied. This external appearance, no doubt, suggested the idea of their 

 being fossil palms, under which name fragments of them may be met 

 with in almost any provincial museum. The scars of fallen branches 

 are abundant, and always exhibit a considerable hollow at the place, 

 as if the branch had rotted out. The fibrous surface of trunks that 

 have been long exposed has a smooth and polished, almost varnished, 

 appearance, produced by the action of the sand when driven against 

 them by the wind. The wood is generally of a dark reddish-brown 

 colour, and contrasts with the lighter-coloured barren and sandy soil 

 on which it rests or' is partially buried. This surface sand rests on 

 a dark-coloured sand and pudding-stone, in which the silicified 

 stems occur, and from which those lying loose on the surface have 

 been washed. This stratum forms the dark-coloured knolls which 

 protrude through the sand, and the stems are seen projecting from 

 the weathered sides of these knolls. They lie horizontally in the 

 sandstone. Newbold says a few have a vertical position, rising from 

 10 to 20 inches above the surface of the sand. linger considers this 

 bed to be contemporaneous with the Tertiary nummulitic limestones 

 of Egypt. The forests which supplied the wood flourished, he 

 believes, to the south, and the trunks were brought into the flat 

 deserts by running water, which carried with it, also, the sand and. 

 mud in which they are now buried. The different density of the 

 woods sorted them in the flood and influenced their transportation, 

 and accounts for the limited number of species, and the remarkable 

 predominance of one of them. 



The wood is converted into chalcedony. The tissues are, on the 

 whole, not well preserved, although occasionally specimens occur in 

 which every cell and vessel is clearly defined. linger detected in 

 some specimens the branching mycelium of a parasitic fungus, pene- 

 trating the cavities of the large ducts, to which he gave the name of 

 Nyctomyces entoxylinus (Chloris Protogsea, p. 8, tab. I. fig. 7). In 

 none of the large series of microscopic preparations which I have 

 examined (21 from the specimens collected by Prof. Owen, two from 

 the Bryson Collection, and two from that of Eobert Brown) have I 

 been able to detect this fungus. In all of them the ducts are filled with 

 transparent chalcedony, which occasionally shows a dark, amorphous 

 and irregular, sometimes branching core, passing down the centre. 



' Quart. Journ. Geol. Soc, vol. iv., p. 349. 



^ Bull. Soc. Geol, France, ser. 2, vol. iii., p. 541. 



