MICHIGAN ACADEMY OP SCIENCE. 149 



Rosaceae sliowe*! that these arise as o]>en iiief;as]>or(>])h.vIls with tiie 

 uiegasporanjiia (ovules) exposed to the air, but tluit gradually the 

 edges fold together, from below first, eventually closing eutirely 

 only shortly before pollination. 



The origin of the enibryo-sae, ''double fertilization" etc., cannot 

 be traced out iu any available fossils. Whatever theory as to the 

 ancestry of the Anthophyta is followed, the explanations as to these 

 structures must 1«' about the same. 



It reuuiins to be ]»ointed out that such branched forms of Ben- 

 nettitineae as AVilliamsonia augustifolia show that the single trunk 

 habit of most of the group was not fixed to so great a degree that 

 the vicinity of this group can not be regarded in the ancestral line 

 of the Antlioi)hyta. Likewise the small leaves of this form with 

 their but slightly lobing may well forecast the small, simple (but 

 strongly ])innately veined) leaves of Magnoliaceae (small leaves as 

 compared with the Cycads and Rennettitineae in general, but large as 

 compared with many Anthophyta.) The strobili of the Rennettiti- 

 neae were about the size of the flowers of the Magnolia. 



?^ummarizing briefly : — the Eusporangiatae among the ferns gave 

 rise to the Pteridospermeae, from which arose two main lines of 

 descent, each accompanied by the development of the strobilar struc- 

 ture. One of these lines, that with bi-sexnal strobili with a ''peri- 

 anth/' gave rise, on the one hand, to the Rennettitineae and, on the 

 other, to the Anthophyta whose most primitive forms are the 

 Ranales, with large strobilar flowers. From these have arisen all 

 other groups of Anthophyta. 



BIBLIOGRAPHY. 



Arber, E. Newell and Parkin, John. On the Origin of Angio- 

 sperms. The Journal of the Linuaean Society. Botany. 38 :29-S0. 

 4 text figures. July 11, 1907. 



Raile}', I. W. and Sinnott, Edward W. Investigations on the 

 Phylogeny of the Angiosperms. No. 2. Anatomical Evidence of 

 Reduction in Certain of the Amentiferae. Rotanical Gazette. 58 :8G- 

 CO. pis. 3-5. 3 figs. July 1914. 



Raillon, A. Dictionnaire de Botanique. Vols. 14. 187G-1892. 



Bancroft, N. A review of Literature Concerning the Evolution of 

 Monocotvledons. The New Phvtologist. 13" :285-:J08. November 

 1914. 



Berridge, E. M. The Structure of the Flower of Fagaceae, and 

 its Bearing on the Attinities of the Group. Annals of Botany. 28 : 

 509-526. 9 text figures. July 1914. 



Bessev, Charles E. Evolution and Classification. Address as 



