part 3] CHAROPHYTA OF THE LOWER HEAEOX BEDS. 189 



the foregoing and in having probably had a persistent eoronula. 

 They are smaller than those of any living TohjpeJla. 

 Obtained in fair quantity from the Limestone-Band. 



Vegetative Remains. (PL VI.) 



A large proportion of the remains of stems and branchlets appear 

 to belong to a single type, designated as A (PL VI, figs. 10-12), 

 of which the following are the characteristics : — 



Stems. — The remains of these consist of numerous short frag- 

 ments. The diameter ranges from c. 250 \x to c. 400 ft, and the 

 rows of cortical cells from about fourteen to twenty. The latter are 

 usually of like diameter and always contiguous. There is usually 

 considerable torsion visible in the cortex, and this is invariably 

 dextral, as in the living Chareifi. The arrangement of the cortical 

 systeni is difficult to elucidate, on account of the fragmentary 

 character of the remains ; but, from the number of rows, it may 

 perhaps be presumed to be diplostichous, that is, having one row 

 of secondary cortical cells to each primary row. This cannot, 

 however, be determined, as there is no marked difference in the 

 diameter or prominence of the rows, and no node-cells have been 

 made out, to indicate the primary series. The cortical cells are 

 evidentl}^ long ; but their length has not been determined, as in no 

 case has an entire cell been found. Portions have, however, been 

 observed, measuring as much as 1250 /x. The ends of the cortical 

 cells seem usually to taper considerably, often to a sharp point ; but, 

 whether these belong to a secondar}^ series, or are the terminal cells 

 of the primary series, is not apparent. 



Brais'chlets. — The remains of these are fairly numerous, but 

 are also extremel}^ fragmentary. They vary in thickness from 

 about 170 to 250 ^. Like those of living species, they show little 

 torsion. The cortex is regular, the number of cells being about 

 fourteen to sixteen, so that the arrangement in this case may be 

 presumed to be diplostichous, as in nearly all living species ; but no 

 trace of bract-cells has been found. Nodes are frequent, and are 

 indicated by a unilateral swelling of the branchlet at the spot, and 

 by the meeting of the bases of the ascending and descending cells 

 in a more or less even circle. The length of the cortical cells of 

 the branchlets also cannot be determined, as in no case has a 

 complete cell been found ; but that the length is evidently very 

 irregular is indicated by the fact that the points of meeting of the 

 apices of the ascending and descending cells do not coincide in 

 adjoining rows. 



The cortical cells of both stems and branchlets are found in a 

 collapsed condition, presumably from desiccation, resembling those 

 of dried specimens of recent species, and therefore appear as 

 grooves instead of c^dinders. 



From the diameter of the stems and branchlets this t^qDc may 

 be presumed to belong to a plant of about the stature of Char a 

 fragifera. 



