154 Mr. F. M'Coy on the Fossil Botany and Zoology 



the relation of the whorls of leaves to the sheaths : I have traced 

 them distinctly in every instance as arising from the free edge of 

 the sheath, and lying either straight, inclining obliquely out- 

 wards, or, as is most commonly the case, completely reflexed, as 

 I have represented in the drawing PL XI. fig. 2 : and their oc- 

 currence in this position may have deceived Messrs. Lindley and 

 Hutton as to their real connexion with the sheaths ; for when 

 the long slender leaves are completely reflexed and pressed in a 

 reversed position against the sheaths, broken specimens may easily 

 have their inferior mistaken for their superior extremities ; and if 

 when in this position the leaves be supposed to point upwards, 

 they will really have the appearance of originating as an inde- 

 pendent whorl of leaves outside of the base of the sheath, as de- 

 scribed in the ' Fossil Flora/ This double arrangement would 

 be so anomalous, that it is the more important to have the means 

 of ascertaining the true relation of those parts in accordance with 

 Brongniart's original view. 



Brongniart describes the stem as smooth, and I find the spe- 

 cimens before me apparently divisible into two groups, one 

 having the stem smooth, the other having it coarsely sulcated 

 longitudinally, as in Catamites. All the botanists alluded to 

 agree in describing the stem of Phyllotheca australis as simple ; — 

 all the sulcated stems I have seen are simple, but a number of the 

 smooth or slightly striated stems are distinctly branched, and in 

 a manner quite distinct from Equisetum. In Equisetum, if we view 

 with most botanists the sheaths as produced by the mere lateral 

 union of the leaves, and thus representing the foliage of other 

 plants, we have the extraordinary character of the branches arising, 

 not as axillary buds originating immediately above and within the 

 base of the leaves, but originating below the joints and external to 

 the sheaths. This is not the case with the fossil before us, in which 

 the branches originate directly. over the joints, and are therefore 

 within and axillary to the sheaths, which may thus, with their 

 appendages, be considered as true leaves, and having the same 

 relation to the branches as in ordinary plants. This character 

 is of such importance, that the resemblance of Phyllotheca to 

 Equisetum is proved by it to be of the most trifling nature, and 

 that there can be no real affinity between them. On the other 

 hand, when compared with Casuarina, the affinity seems to me 

 to be exceedingly strong, although botanists have not, I believe, 

 hitherto so considered it. The Casuarina are exogenous weeping 

 trees, with slender cylindrical branches, their shoots regularly 

 jointed, longitudinally sulcated, and surrounded at the joints with 

 toothed sheaths as in Equisetum ; while the branches originate 

 either in a verticillate or irregular manner immediately above the 

 joints and within the sheaths, showing a perfect agreement with 



