and a Carpolite from Nova Scotia, 



109 



stems, and a few stigmaroid areoles are perceptible on the lower sur- 

 face of the stump. 



The woody axis has entirely disappeard, nor does any mineral 

 charcoal appear in the base of the cast. It has either been en- 



Fig. 3. 



tirely removed by decay, or has been washed out by the waves before 

 the hollow bark was filled up. 



As this trunk appears to belong to a species not previously de- 

 scribed, and we have a better knowledge of its parts and mode 

 of growth than of those of most of the named species, I may pro- 

 pose for it a specific appellation, and would call it Sigillaria 

 Browniiy in commemoration of the many interesting discoveries 

 in relation to these plants made by my friend Richard Brown, 

 Esq., of Sydney, Cape Breton. 



The following are the most important points relating to 

 Sigillanoe in general, illustrated by the specimen above-de- 

 scribed :— 1. The evidence of the exogenous growth of Sigillaria. 

 The growth of the trunk took place, as I have elsewhere main- 

 tained,* by the introduction of new woody wedges in the axis and' 

 by additions to the surface of the axis and to the inner bark, after 

 the manner of exogenous stems. When the present trunk had nine 

 rows of scars it was only three inches in diameter, perhaps 

 much less, and as it grew in height the base expanded in such a man- 

 ner as to increase the distances between the scars and the distances 

 between the vascular punctures in the scars, while new rows of 

 leaves were added above until the number amounted to about 2G. 

 The same appearances in a species quite distinct from the present 



• Quart. Journ. Geol. Soc. vol. x. p. 32. 



