EQUISETALES— CALAMAEIEyE— C YCLOCLADIA. 1 69 



Under these conditions, according- to the rules of nomenclature now 

 generally obtaining in both botany and paleontology, Cydocladia should 

 have priority over Calamitina or any other name proposed since 1834 as a 

 designation for the stems of this group. It is unfortunately true that con- 

 venience, usage, appropriateness of etymology, or even personality, have 

 had as much influence on nomenclature in paleobotany as in any other 

 allied science. 



For the use of a dual nomenclature, such as the employment of Cydo- 

 cladia for the stems of the Macrostachian or Calamites verticillatus type and 

 Macrostadiya or Huttonia for the fruiting spikes, there is abundant precedent 

 in paleobotany, even within the Calamarian family itself 



GYCLOCLADIA BRITTSII 11. sp. 



PI. XLIX, Fig. 1. 

 1897. Cydocladia sp., D. White, Bull. Geol. Soc. Amer., vol. viii, p. 297. 



Stems attaining a width of 10 cm. or more, divided into short inter- 

 nodes, of which about one in eight is occupied exclusively by large scars; 

 fructification or rameal verticils 2.5 to 3.5 cm. distant from border to border, 

 consisting of a transverse compact row of rounded or oval disk-like depres- 

 sions, each 1.5 to 2 cm. in longitudinal diameter and about 1.75 cm. trans- 

 versely, provided with an inner cicatrice about 5 mm. in diameter; foliate 

 nodes 7 to 9 in number between two nodes with large cicatrices, 10 to 3 

 mm. distant, the internodes becoming uniformly shorter in passing upward, 

 and marked by narrow transverse bands containing the leaf scars; internodal 

 surface finely lineate longitudinally; leaf scars transversely oval, not con- 

 tiguous, 1.5 to 2 mm. in greater diameter, 1 mm. in longitudinal diameter, 

 and about 4 mm. from center to center, the central points being punctate or 

 slightly mammillate. 



The general characters of this species, of which I have seen but a few 

 fragments, can better be learned from the figure, PI. XLIX, Fig. 1, than 

 from a description. Both the figured specimen and another example are 

 slightly distorted by pressure. The back of the larger fragment, which 

 shows a portion of a verticil of large scars at the top, preserves the other 

 side of the stem. This back portic^i has still a third verticil of large scars. 



