Maryland Geological Survey 381 



extremely doubtful character. A similar course is pursued in regard to 

 the affinity of some of the fragmentary detached specimens of 

 Nageio'psis, so called, from higher horizons in the Potomac Group. In 

 cases where there is absolutely no evidence that they are so related they 

 have been referred to Podozamites or Zamites, genera broad enough to 

 include them without the implications and the contravention of the 

 generic diagnosis which would be involved in retaining them in 

 Nageiopsis. 



Throughout the whole order Coniferales the phyllotaxy is as a rule 

 spiral, more rarely it is cyclic in character. A true distichous or two- 

 ranked arrangement is unknown, although a great many conifers with 

 a spiral ph3dlotaxy are markedly distichous in habit, as for example, 

 Taxodium, Araucaria, Tumion, Taxus, etc. It seems probable that 

 Nageiopsis was no exception to the general rule ; in fact some specimens 

 show leaves inserted on all four sides of the stem. More often, how- 

 ever, the exact method of attachment is obscured, but the more or less 

 twisted base argues strongly for a spiral phyllotaxy. A distichous habit 

 is strongly emphasized in fossil impressions which have been subjected 

 to more or less compression, just as in the case of pressed herbarium 

 specimens. 



There is a suggestion in some specimens of Nageiopsis that the base 

 was markedly decurrent as in the modern Araucaria Bidwilli. This 

 is furnished by the extraordinarily large size of some of the stems, 

 which are irregularly expanded and contracted as if certain of the 

 decurrent leaf bases had been spread out somewhat in the flattening 

 which accompanied fossilization. This feature is especially well shown 

 in the portion of the specimen of Nageiopsis zamioides previously figured.* 

 The stem is broad at the base, giving off on either side sub-opposite leaves 

 with apparently sheathing decurrent bases. Above their insertion the 

 stem is considerably narrowed, passing to a portion obscurely preserved. 

 Above this point it is at least twice as broad, contracting to form the 

 narrow base of the right-hand leaf, while just above the main stem is 

 continued as a much narrowed twig, the next leaf above, that on the 

 left, having its base concealed behind the twig. In no instance is the 



__i Berry, Proc. U. S. Natl. Mus., vol. xxxviii, 1910, p. 191, fig. 1. 



