Professor Bommer on Lcpuiocarpon. 21 
lateral furrows in the sporophyll of Lepidocarpon Lomaxi , a fact on 
which I have laid no stress, as it has no evident beating on the 
question as to the nature of the integument. 
The author considers the species L. Wildianum especially 
favourable to his interpretation, but I have not found any essential 
difference between the two species; in L. Wildianum also there is 
evidence for the presence of a laminar margin distinct from the 
integument . 1 On a consideration of all the facts, it seems clear that 
the integument in the genus Lepidocarpon was a new formation, not 
represented in the young sporophylls or in those of ordinary 
Lepidostrobi. Neither is the velum of Isoetcs formed by the in¬ 
folded margins of the sporophyll, as Professor Bommer, no doubt 
by an oversight, states (p. 135); his own figure shows that this is 
not the case . 2 The velum of Isoetcs springs partly from the saddle 
at the distal end of the sporangium, partly from the upper surface 
of the sporophyll-base, but not from its margins; like the integument 
of Lepidocarpon it is a new formation—an indusium. I agree with 
Professor Bommer that the integument of a seed is also a sort of 
indusium (p. 136). 
The statement that in Lepidocarpon the sporangium is protected 
by the whole of the sporophyll is true, but with the reservation that 
this protection is only carried out with the help of a new organ, the 
integument, specially adapted to this function. That the sporophyll 
as a whole takes part in the formation of the seed-like organ is a 
real point of difference from a typical seed, as I had already 
stated . 3 
In conclusion our author remarks that there are two facts 
which materially reduce the morphological importance of the 
integument of the megasporangia in Lepidocarpon (p. 136). One of 
these facts is the presence of a similar protective envelope around 
the microsporangia. On this point I have nothing to add to what 
is said in my paper (p. 322). An envelope originally common to 
both kinds of sporangia may well have been retained and further 
developed on the female side only, where its functions would obviously 
be more important. In our fossil there is already a considerable 
difference between the integuments of the two organs, for that of 
the microsporangium forms only a very partial investment . 4 
M. c., p- 316, PI. 42, Fig. 18. 
2See also Campbell, Mosses and Ferns, l'ig. 144, 11 - 
* 1 . c., p 321 . 
4 1 c., p. 313. 
