152 MORPHOLOGY OF SPERMATOPHYTES 



It is hardly possible that such a sequence represents the 

 relative age of the distinct differentiation of these groups, for 

 it can not be corroborated upon any theory of morphological 

 relationship. 



LITERATURE CITED 



1. CARRUTHERS, W. On gymnospermatous Fruits from the Second- 



ary Rocks of Britain. Journal of Botany 5 : 1 seq. 1867. 



2. SOLMS-LAUBACH, H. Ueber die Fructification von Bennettites 



Gibsonianus Carr. Bot. Zeit. 48 : 789-798, 805-815, 821-833, 843- 

 847. pis. 9-10. 1890. 



3. SOLMS-LAUBACH, H. Fossil Botany. 1891. 



4. WIELAND, G. R. A Study of some American Fossil Cycads. Part 



I. The Male Flower of Cycadeoidea. Am. Jour. Sci. IV. 7: 

 223-226. pis. 2-4. 1899. 



5. WIELAND, G-. R. A Study of some American Fossil Cycads. Part 



III. The Female Fructification of Cycadeoidea. Am. Jour. Sci. 



IV. 7: 383-391. pis. 8-10. 1899. 



6. SCOTT, D. H. Studies in Fossil Botany. 1900. 



7. WIELAND, G. R. The Yale Collection of Fossil Cycads. The Yale 



Scientific Monthly 6: March, 1900. 



