476 THE CARBONIFEROUS SYSTEM. 



Var. a. Areoles large, distant ; bark more or less smooth. This 

 is the most common variety, and extends throughout the Coal for- 

 mation. 



Var. b. Areoles large, separated by waving grooves of the bark. 



Var. c. Similar, but ridges as well as furrows between the areoles ; 

 var. undulata of Goeppert. 



Var. d. Areoles small, separated by waving grooves. 



Var. e. Areoles moderate, in vertical or diagonal fuiTOWS separated 

 by ridges ; var. Sigillarioides of Goeppert. 



Var. / Areoles small ; bark finely netted with wrinkles or striaj. 



Var. g. Areoles surrounded by radiating marks, giving a star-like 

 form; var. Stellata of Goeppert. The only specimen I have seen 

 was found by Dr Harding in the Lower Carboniferous Coal measures 

 of Horton. 



Var. h. Areoles small, or obscure and infrequent. Surface covered 

 with fine uneven strife. My specimens were collected by Mr Brown 

 in the Middle Coal measures at Sydney. 



Var. i. Areoles narrow, elongate, bark smooth or striate. 



Var. k. Alternans, with areoles in double rows on broad ribs sepa- 

 rated by deep furrows. Probably old furrowed roots. 



Var. I. Knorroldes. Prominent bosses or ridges instead of areoles. 

 These are imperfectly preserved specimens. 



The varieties a, 6, c, e, /, have been seen attached to trunks of 

 SigiUarice of the group distinguished by broad and prominent ribs — 

 Sigillaria proper of the above arrangement. St/'gmarice, like Sigillaria', 

 are exceedingly abundant in the Middle Coal measures, and are com- 

 paratively rare in the Lower Carboniferous and newer Coal formations. 



Calamodendron, Brongn. 



1. Calamodendron approxhnatiim, Brongn. (Fig. 162). This plant is 

 evidently quite distinct from Calamites proper. The Calamite-like 

 cast is a pith or internal cavity, surrounded by a thick cylinder of 

 woody tissue consisting of scalariform vessels and woody fibres with 

 one row of round pores ; external to this is a bark of cellular and 

 bast tissue. The structure appears to be allied to that of Sigillaria 

 and is one of the most common in the beds of bituminous coal. M. 

 C, Sydney (R. Brown) ; M. C, Joggins, Pictou (J. W. D.) ; Coal 

 Creek (C. B. Matthew). 



2. C. obsciirum, spec. nov. This is a Calamite-like fragment 

 found in a block of Sydney coal, in the state of mineral charcoal. 

 The external markings are obscure, but the structure is well preserved. 

 It differs from the last in having large ducts with many rows of pores, 



