408 



BENNETTITALES 



[CH. 



of lociJi are bounded by flattened cells and there are 10 — 20 

 loculi in each of the two rows: de- 

 hiscence of the individual locuh occurs 

 in the middle of the inner wall. 



f^ 



Cycadeoidea Marshiana Ward. 



This Lower Cretaceous Black Hills 

 species^ affords an admirable example 

 of a method of branching exhibited by 

 some stems: as shown in Wieland's 

 photographs^ there may be five or six 

 large and massive trunks all in the 

 same stage of fructification, differing 

 but Httle in size and forming a cluster 

 resembhng independent plants growing 

 in close proximity to one another. 

 There is apparently no central or 

 major axis and the habit is therefore 

 very different from that of a branching 

 Byicldandia. Cycadeoidea Marshiana 

 bore large ovulate pyxiform strobih 

 projecting slightly beyond the leaf- 

 bases; they are 5 cm. long with a 

 maximum diameter of 3-5 cm. and 

 have an elongated receptacle bearing 

 short scales and sporophylls. The 

 apical bud of one of the trunks shows 

 particularly well in transverse section 

 the dense ramental packing between the bud-scales*. Similar 

 clusters of short and thick trunks occur in Cycadeoidea swperha 

 and other American species. 



In the small bisporangiate flowers of this species* the micro- 

 sporophyUs, 11 or 12 in the verticil, are characterised by the 

 presence of a ventral furrow which, as Wieland suggests, may be 

 comparable on a much simpler scale with the winged sporophylls 

 of Cycadeoidea colossalis (fig. 533). The disc splits up at a distance 



Fia.532. Cycadeoideadacotensis. 

 Synangium in longitudinal 

 section showing the thick 

 pedicel, the line of dehiscence, 

 and two locuU with a few 

 microspores. (After Wieland; 

 X 40.) 



1 Ward (98) p. 208. 

 » Ibid. PI. XTX. fig. 5. 



' Wieland (06) Pis. vn. — ^ix., xn., xni. 

 * Ibid, passim; (12). 



