156 Mr Nicol on Fossil Woods 



Of those retaining the perfect structure, a very fine example 

 occurs in a specimen, which, if the label has not been misplaced, 

 was found at the bottom of the cliff, about three miles south 

 from Newcastle. There are several small rents in it, but these 

 seldom extend through more than three of the annual layers, 

 and they are filled with white calcedony. A representation of 

 this specimen, exhibiting a portion of one of the rents, calcedonic 

 veins, is given in Plate III. Fig. 1. 



Of all the specimens in this collection, the above is the only one 

 in which, throughout its whole extent, the ligneous structure has 

 sustained no modification. In some, the structure, although 

 perfect in certain parts, is modified in a most singular and di- 

 versified manner in other parts ; and, in others, there is nothing 

 but the modified structure observable. Figure 2. Plate III. is 

 a magnified representation of a portion of a specimen, in which 

 the reticulated structure rather predominates over modified por- 

 tions. In some few parts of it the medullary rays and concen- 

 tric partitions, preserve nearly their natural positions ; but in 

 the greater part of the whole, the medullary rays are bent into 

 curves, with very different degrees of obliquity. The upper- 

 most layer has these rays bent into a zig-zag form ; but it will 

 be observed, that however much they are contorted, they may 

 be traced individually into the most perfect parts. The reticu- 

 lated structure in the under part of the uppermost layer is obli- 

 terated in consequence of the compression of the concentric 

 partitions. This is a most curious and interesting specimen, 

 and its locality is the Lake Macquarrie, about twelve miles from 

 Paramatta. 



Several of the specimens present a structure somewhat similar 

 to the above. In many of them, however, the modified greatly 

 predominates over the perfect structure. Figure 3. Plate III. 

 is an example of this kind. The under part of the figure is the 

 only spot in the whole specimen where the regular net-work is 

 observable. All the rest of the specimen, which is more than 

 ten times the extent of the portion represented, is more or less 

 in the modified state of the upper part of the figure. Through- 

 out the whole of the distorted part, the concentric partitions 

 have vanished, and only the bolder of the medullary rays, 

 which are more or less bent into a zig-zag form, present them- 

 selves. 



