86 BOTANICAL GAZETTE [august 



and in any given case the proper initial attitude is to hold that 

 either mode of origin may have been the source of the synangial 

 state as it now appears" (Bower 7). Let us seek out first the 

 facts .which might appear to harmonize with the "reduction 

 theory." If this hypothesis is the correct one for the Lepidophytes, 

 Cantheliophorus, with its elaborate bisporangic sporangiophore 

 expanded platelike in the median vertical plane of the sporophyll, 

 would be looked upon as the representative of some primitive 

 ancestral type, from which by reduction and simplification the 

 Lycopods, with a soHtary median sporangium resting 'directly upon 

 the pedicel of the sporophyll, might have resulted. Are there any 

 structural details in Cantheliophorus which are generally con- 

 ceded to be primitive? The distal attachment of the sporangia 

 is often considered to be such, but this opinion has developed so 

 largely out of certain theories of descent, themselves resting often 

 upon very insecure foundations, that while it should not be for- 

 gotten in summing up the evidence, it can hardly be thought of as 

 having much weight. Assuming the correctness of this hypothesis, 

 we might expect to find in the more reduced of several groups 

 vestiges of structures which are functional or at least more ex- 

 tensively developed in ancestral forms or in the less reduced 

 descendants of these ancestral forms. I have already quoted the 

 suggestion by Scott that the ventral sporange-bearing prominence 

 upon the pedicel of Spencerites may be the vestige of a sporan- 

 giophore. Miss Benson figured and discussed at some length 

 Mazocarpon from the Upper Carboniferous, with its great central 

 core of sterile tissue and two lateral "sporogenous regions," and 

 in the same paper also a new heterosporous form, Lepidostrohus 

 mazocarpon, from the Lower Carboniferous of Burntisland, Scot- 

 land, likewise with a great central mass of sterile tissue, both in 

 the microsporangia and megasporangia, with the sporogenous 

 tissue arranged in an arc about it above, and she states that "it 

 would be a very natural sequence that the sporogenous region of a 

 single sporangiophore should become confluent, and the gradual 

 reduction of the sterile tissue to a mere ' archesporial pad' and 

 pedicel would next follow." 



