530 Sykes and Stiles. — The Cones of the Genus Selaginella. 
megaspore, round the base of which were clustered three minute aborted 
spores (Fig. 13 c, PL XLI). In other cases the sporangium contained two 
large and two small spores, or two large and one small spore, &c. 
There are two or three rows of cubical cells with feebly lignified walls 
in the stalk of the mature sporangium. There is also slight lignification at 
the base of the ligule in this species. 
General Remarks. 
A. Comparison with Lycopodium and other genera. 
(i) The form of the sporophyll. The method of protecting the 
sporangia by means of sporophylls with both upward and downward 
extending portions is well known to have been common among the ancient 
Pteridophyta. The sporophyll both of L^epidostrobus 1 and of Spencerites 2 
had a more or less well-developed dorsal lobe, and the sterile segments 
of the sporophylls of Cheirostrobus 3 had a downward extending portion. 
Mr. Watson asserts that in Mesostrobus 4 also the sporophyll had a similar 
form, but this statement does not appear to be supported by his figures ; 
consequently it is not possible to make any clear comparison between 
this and the other genera, and the discussion on pp. 393-3 of his paper 
is somewhat obscured. 
When we find such a series of forms in a single genus as has now been 
demonstrated in both Lycopodium 5 and Selaginella , it becomes difficult to 
place entire confidence in any comparison, based on the forms of the sporo¬ 
phyll, between different genera of widely separated geological ages. 
Watson 6 has grouped together Miadesmia , Bothrodendron , and 
Selaginella , and it is true that these genera resemble one another to some 
extent in the position of the attachment of the sporangium. But here 
it must be remembered that while we have no certain evidence as to where 
the sporangium originated in the fossil genera, we do know that in Selagi¬ 
nella it arises from stem tissue, and in some species, even in the adult cone, 
is inserted on the stem above the leaf. 
On the other hand, the presence of the dorsal lobe in two probably 
primitive species of Selaginella suggests a comparison with Lepidostrobus , 
Spencerites , Lycopodium alpinum , &c. It is, of course, possible that this 
method of protecting the sporangia may have been evolved over and over 
again ; still it would appear to be a character at least as valuable for 
purposes of comparison as is the particular point of attachment of the 
sporangium. 
1 Williamson, W., 1893; Maslen, A. J., 1899, p. 371, Fig. 22, PI. XXXVII; Fig. 36, 
PI. XXXVIII. 
2 Berridge, E. M., 1905 ; Watson, D. M. S., 1909, Text-fig. 4, p. 389. 
3 Scott, D. H., 1897, P* 7 (Diagram), 4 Watson, D. M. S., 1909, p. 393. 
5 Sykes, M. G., 1908 (2). 6 Watson, D. M. S., 1909, p. 391. 
