148 



MORPHOLOGY OF SPERM ATOPHYTES 



FIG. 103. Cycadeoidea Dacotensis, 

 a very small part of a some- 

 what tangential longitudinal 

 section of a strobilus, to show 

 in side view the septa of a syn- 

 angium, x 8. From prepara- 

 tion made by G. R. WIELAND 

 from specimen in Yale Univer- 

 sity Museum. 



We have described the strobilus 

 of Cycadeoidea Dacotensis as consist- 

 ing of a sheath of overlapping bracts, 

 within which microsporophylls bear- 

 ing Marattialike synangia occur. 

 Within the microsporophylls, and 

 towards the base of the strobilus, 

 there is discovered what at first 

 sight appears to be merely the conic- 

 al apex of the axis of the strobilus, 

 but which proves to be the ovulate 

 region (Fig. 104). The conical re- 

 ceptacle is covered all over with the 

 characteristic stalked seeds and " in- 

 terseminal scales." In this case the 

 " receptacle " really resembles an 

 axis, and is of the ordinary Gymno- 

 sperm type; while in Bennettites 



and certain species of Cycadeoidea the receptacle is flattened. 



This elongated ovulate axis is not always associated with a bi- 



sporangiate strobilus, as it occurs in strictly ovulate strobili. 



In Fig. 105 there is 



shown a transverse 



section of a young 



ovulate strobilus of 



Cycadeoidea colossal- 



is, whose axis is of 



the elongated type, as 



in the bisporangiate 



C. Dacotensis (Fig. 



101), but which is 



invested directly by 



the ensheathing ster- 

 ile bracts. The illus- 

 tration also shows 



some of the character- , 



, . , FIG. 104. Cycadeoidea Dacotensis, longitudinal section 



StlC ramenta Which through basal portion of strobilus, showing at the 



Were packed between left portions of synangium-covered sporophylls, and 



the superficial sheath at the right the ovulate region of the strobilus ' x 4 - 



j , ,. /. From preparation made bv G. R. WIELAND from 



and the OVUlllerOUS specimen in Yale University'Museum. 



