246 BOTANICAL GAZETTE [march 



and Helminthostachys, whose pitting is strikingly similar to that of 

 the seed plants, resembles closely the type I have found in the lower 

 gymnosperms, in Ginkgo and the araucarians, forms which are to 

 be described later. 



To Professor R. B. Thomson, under whose direction this 

 work has been carried on, is due my grateful acknowledgment of 

 his invaluable assistance and advice. I am indebted also to both 

 Professor Thomson and Professor J. H. Faull for material, some 

 of which was obtained originally through the kindness of the 

 Director of the Royal Botanic Gardens, Kew. 



University of Toronto 



LITERATURE CITED 



1. Bancroft, N., On the xylem elements of the Pteridophyta. Ann. Botany 



25:745-758. 1911. 



2. Boodle, L. A., On some points in the anatomy of the Ophioglossaceae. 



Ann. Botany i3:377~394- 1899. 



3. DeBary, A., Comparative anatomy of the Phanerogams and Ferns, pp. 161 

 -162. 1884. 



4. Farmer, J. B., and Freeman, W. G., On the structure and affinities of 

 Helminthostachys zeylanica. Ann. Botany 13:421-445. 1899. 



5. G wynne- Vaughan, D. T\. On the real nature of the tracheae in ferns. 



Ann. Botany 22:517-523. 1908. 



1m 



gamen. Dissertation. 1910. 



Mem 



Petersbourg 19:1-207. 1872. 

 Strasburger. E.. Das Botar 



EXPLANATION OF PLATES XI, XII 



Fig. 1 — Ophioglossiim vidgatum: transverse section of rhizome; X5°- 

 Fig. 2. — Helminthostachys zeylanica: transverse section of rhizome; X35- 

 Fig. 3. — Botrychium virginianum: transverse section of rhizome; X4°- 

 Fig. 4. — Ophioglossum vulgatum: root, transverse section; X210. 

 Fig. 5. — Botrychium virginianum: root, transverse section; X120. 

 Fig. 6. — Helminthostachys zeylanica: root, transverse section; Xi4°- 

 Fig. 7. — Ophioglossum vulgatum: metaxylem of root showing pitting; 



X875. 



