UNUSUAL TYPES OF PETRIFACTION. 
37 
Magnesia, MgO 
.. 1. 17 
none 
Manganese oxide, MnO . . . 
.78 
.20 
Iron protoxide, FeO 
none 
8-34 
Iron peroxide, Fe^ O3 
I.OI 
40.15 
Alumina, Ah O3 
4.44 
Chlorine, Cl 
.01 
none 
Fluorine, F 
3.00* 
none 
Carbon, C (in organic com 
bination) 
.18 
.40 
Water hygroscopic, IE 0 
— .22 
•32 
102.42 
100.54 
Less oxygen — fluorine . . . . 
1.26 
101.16 
ebted largely to Mr. H. Bowley for these 
results. 
The deposits in which these fossil woods are imbedded 
were probably laid down in an ocean, since glauconite, a 
silicate of iron and potash, characteristic of oceanic deposits 
formed at no very great distance from land, is freely as- 
sociated with them. At first sight it is difficult to account 
for the presence of a light coniferous wood in such a situation. 
It is not uncommon, however, for barnacles at the present 
day to so increase in numbers on a floating piece of pine as 
to sink it permanently, and in some such way the fragments 
of C edroxylon found their way to the bottom of the Mesozoic 
Sea. The means by which they were preserved from bac- 
terial destruction, and the details of the processes involved 
in the molecular replacement of cellulose and lignin by 
calcium and iron phosphates, still remain to be worked out. 
That timber even in those remote days was subject 
to the destructive attacks of boring organisms is evident 
from the numerous tunnels of such creatures in almost 
every specimen of this wood. These holes range in diameter 
from 2 to 15 mm. and are filled with a mixture of granular 
lime phosphate, grains of quartz and of glauconite. A 
section of one is seen in Fig. 19, Plate XIII. Embedded in 
this filling are clusters of spherical brown bodies ranging in 
diameter from 0.02 to 0.10 mm. Similar bodies are considered 
by Seward f to be the fossil excreta of wood boring beetles, 
etc. Apart from this suggestion we have no evidence as to 
whether the boring was done by land insects before the 
wood reached the water, or by marine organisms, such as 
Teredo, after drifting out to sea. 
* From weight of CaF 2, 2.97 and 3.05 ; from CaSO 4 , 2.94 and 
3.06. 
t Seward, A. C. : Fossil Plants, Vol. I, p. 107. 
