A Contribution to our Knowledge of Rachiopteris 
cylindrica, Will. 
BY 
N. BANCROFT. 
With Plates XXVI and XXVII and seventeen Figures in the Text 
Contents. 
PAGE 
PAGE 
I. 
Sources of Material, and 
Ac- 
3. Roots ..... 
548 
KNOWLEDGEMENTS . 
531 
i. Development 
548 
II. 
Distribution and Horizon 
OF 
ii. Anatomy and Histology 
549 
R. cylindrica 
532 
iii. Branching .... 
55* 
III. 
Detailed Description of 
THE 
IV. 
Organs in Association with 
Organs of R. cylindrica . 
532 
R. cylindrica .... 
55* 
1. Stems .... 
533 
1. ‘ Axes ’ of various orders . 
55* 
i. General description 
533 
2. Sporangia ..... 
552 
ii. a type .... 
535 
V. 
General Discussion . 
553 
iii. /3 type .... 
538 
1. The Significance of the Occur¬ 
iv. Histology 
539 
rence of a and j3 types 
553 
v. Branching . 
542 
2. The Relationships of R. cylin¬ 
2. Petioles .... 
545 
drica ..... 
554 
i. Development 
545 
3. Theoretical Considerations 
560 
ii. a type .... 
546 
i. The Primitiveness of the Stelar 
iii. P type .... 
546 
Condition .... 
561 
iv. Histology 
548 
ii. The Homology of the Leaf . 
562 
v. Branching 
548 
VI. 
Summary . 
563 
I. Sources of Material, and Acknowledgements. 
T HE series of preparations of Rachiopteris cylindrica upon which 
the following description is mainly based, were handed to the writer 
by Prof. F. W. Oliver, to whom grateful acknowledgements are due, not only 
for the material, but for the opportunity to carry out this investigation 
at University College, London. 
The writer also desires to thank Prof. F. E. Weiss, through whose 
kindness some valuable evidence has been obtained from the slides of 
the Cash and other collections, at Manchester University; Dr. A. Smith 
Woodward, for permission to examine and make drawings from the 
Williamson and General collections, at the British Museum ; Prof. A. C. 
Seward and Dr. E. A. N. Arber, for similar opportunities with regard to 
[Annals of Botany, Vol. XXIX. No. CXVI. October, 1915.] 
