BENNETTITALES 75 



Bennettitales as an "inflorescence" rather than a "flower"; and he 

 has enriched the terminology of the strobilus further by adding 

 pteridostrohilus as a stage before the proanthostrobilus, to include 

 the grouping of fernlike microsporophylls and megasporophylls in 

 monosporangiate strobili. Wieland (30) has also dissented from 

 the substitution of the new term hemiangiosperms for the long-used 

 proangios perms of Saporta. The possible relationship of gymno- 

 sperms to angiosperms does not come within the province of this 

 volume, but in connection with the structure of the strobilus of Ben- 

 nettitales its responsibility for speculation in reference to the origin 

 of the angiosperms should be known. 



In any event, it is safe to conclude that if the Cycadofilicales gave 

 rise to the strobilus-bearing cycadophytes, there were at least two 

 lines of development: one leading to forms with bisporangiate strobili 

 (Bennettitales), and the other te forms with monosporangiate strobili 

 (Cycadales) . 



THE MICROSPORANGIUM 



Wieland's investigations (22) of Cycadeoidea indicate that the 

 microsporophylls (stamens) are remarkably uniform in character. 

 In number they range from ten (C. Jenneyana) to twenty (C. daco- 

 tensis). In form they are elongated, pinnate, fernlike leaves, with 

 about twenty slender pinnae, beneath which there are borne two 

 lateral rows of close-set synangia (fig. 60). It has been suggested 

 that these sporophylls should be called bipinnate, on the ground that 

 the synangia represent ultimate pinnules. The only advantage to 

 be gained from this somewhat doubtful interpretation is that it serves 

 to distinguish the microsporophylls of Cycadeoidea (so far as studied) 

 from the simpler ones of Williamsonia. The sporophylls are united 

 at base into a "disk" and become free and pinnate above the ovulif- 

 erous apex of the receptacle. The condition might be described 

 as that of monadelphous stamens, and it suggests the monadelphous 

 stamens of Welwitschia (Tumboa), in which the strobilus is also 

 bisporangiate. All the microsporophylls are inflexed, so that the 

 upper third lies with its back against the ovuliferous apex of the 

 receptacle, and its synangia against those of the rest of the sporophyll 

 (figs. 59 and 60). We must imagine the straightening and possible 



