130 G. R. Wieland — Cycadeoidean Flower-hud Structure. 



its (?) microspores go to show that with continued sterilization 

 of a megaspore-bearing crown of whorl ed, equitant, opposite 

 or circularly emplaced sporophylls finally reduced to bract-like 

 form, these might unite to enclose a single spore, the nucellus, 

 and thus surround and fuse with it as a ribbed, bundle-sup- 

 plied, apically chambered, protecting wall ? This indeed is 

 the analogy which must best explain the seed and show why 

 ancient seeds are the more complex, are leafy, and have their 

 major and secondary ribs, their canopy and lagenostome. The 

 seed is, in short, as much a branch, or better a compacted and 

 sterilized crown of sporophylls as a simply staminate flower ; 

 while a seed and its stamens is thus primarily analogous to a 

 bisporangiate strobiloid crown, and either taken alone, to a 

 simple monosporangiate crown. Just as the strobilus and the 

 flower are the homologues of primitive crowns of simple, 

 spore-bearing leaves, so it seems that the seed is the first result- 

 ant of a process of reduction from an apical group of fertile 

 fronds, — a dyad in case of platyspermic forms; a triad, quatrad 

 or pentad of such fronds in the case of more complex seeds 

 like those of the Conostoma group. 



To further illustrate the explanation of the seed canopy and 

 lagenostome here given I may best briefly refer to a fine new 

 type of seed from the Calciferous sandstone series of the 

 Lower Carboniferous rocks of Petty cur, Fifeshire, Scotland, 

 very recently described by Miss Benson.* This seed is about 

 four millimeters in length and enclosed by a cupule. Eight 

 bundles traverse the tissues of the cupule and the same num- 

 ber the inner flesh. That is to say, the seed wall may be con- 

 ceived to arise from fusion of two alternant whorls of eight 

 members each. But easily the most striking feature of this 

 seed is its finely developed apical frill and its wholly reduced 

 lagenostome, clearly brought to view in fig. 8 ; while in fig. 

 9 I have modified Miss Benson's figures slightly so as to 

 emphasize the frill region. Also the dotted line (L) outlines 

 the hj^pothetical position of the lagenostome of this same seed 

 in its more primitive condition before marked reduction had 

 set in. And it will at once be noted that the general form and 

 relation of parts thus had is essentially that seen in Physos- 

 toma elegans, which I am thus bound to consider a simple 

 and primitive, but at the same time much reduced type of 

 seed, in one sense much, rather than little, specialized as 

 hitherto held. Indeed after studying original sections from 

 my own collection this interpretation of the apical relations in 

 Physostoma hardly seems to admit of any doubt. As observed 



* Sphcerostoma ovale (Conostoma ovale et intermedium Williamson), a 

 Lower Carboniferous Ovule from Pettycur, Fifeshire, Scotland ; by Margaret 

 J. Benson. Trans. Roy. Soc. of Edinburgh., vol. L, Part I (No. 1), pp. 15 

 and 2 pis. Jan., 1914. 



