Sykes and Stiles .— The Cones of the Genus Selaginella. 531 
Unfortunately our knowledge of the fossil Selaginellites 1 is insufficient 
to make it possible to decide to which of the Selaginella types they most 
closely approximated. The exact relation of the sporophylls was not 
apparent in Halle’s specimens. Selaginellites Suissei 2 is more reminiscent 
of Selaginellapumila than of the other types, though we do not think much 
value can be attached to the suggestion. Its multiseriate cones and more 
numerous megaspores mark this fossil species sharply off from Selaginella. 
A more detailed comparison between the series of forms of sporophyll 
found in the two genera Lycopodium and Selaginella may prove to be 
of some interest. The remarkable resemblance between the sporophyll 
of S. pumila and that of Lycopodium cernuum , alpinum , &c., has been 
pointed out above. In both cases the dorsal flap of the sporophyll and the 
groove on the under surface of its stalk 3 efficiently protect the sporangium 
vertically below it. The main difference in the sporophylls of these species 
consists in the nature of the flap, which in L. alpinum and S. pumila is 
entirely a free down-growth, as it appears to have been in Lepidostrobus , 
while in L. cernuum it is further modified by adaptations connected with the 
large mucilage cavity. 4 
One of us 5 has already expressed the conviction, as one of the results of 
a comparative study of the sporophylls of L^ycopodium , that this dorsal 
flap is a primitive feature in that genus; its occurrence in two avowedly 
primitive species of the genus Selaginella appears to us to be suggestive. 
vS. helvetica may be compared with L. inundatum. In both forms the 
dorsal flap is no longer developed, but a small ridge or swelling is now 
present which appears to us to represent its reduced remains. vS. Helvetica 
seems to stand between S.pumila and such forms as 5 . Vogelii much in the 
same way as does L. inundatum between L. cernuum and the simpler types 
of Lycopodium. On the other hand, we know of no forms of sporophyll 
in the genus Lycopodium which are so clearly intermediate as are the sporo¬ 
phylls of S. flabellata and caulescens in the genus Selaginella. 
The simpler Lycopodiums differ however from those species of the 
fourth type of Selaginella in which there is no sign of a dorsal projection, 
and are more closely comparable with spinosa , the sporophyll of which 
appears to be reduced ; in them there has been no development of any 
fresh adaptation for the protection of the sporangium such as has occurred 
in the dorsiventral Selaginellas. 
1 Halle, T. G., 1907. 2 Zeiller, R., 1906. 
3 See Lang, W. H., 1908, p. 360, Fig. 2. This groove is hardly comparable with the curious 
furrow on the lower surface of the sporophyll stalk in BotRrodendron (Watson, D. M. S., 1908, p. 51, 
Text-fig. 1). 
4 Lang, W. H., 1908; Sykes, M. G., 1908 (2). It appears as yet uncertain to which of these 
two forms Spencerites may be most closely compared (Watson, D. M. S., 1909), since the evidence as 
to whether or no there was cohesion between the sporophylls of that genus is not yet conclusive. In 
either case it does not seem necessary to discuss Mr. Watson’s unauthorized extension of Dr. Lang’s 
explanation of Spencerites to Mesostrobus and other genera. 5 Sykes, M. G., 1908 (2). 
