j 
A 
: 
Haynes: AYTonia 59 
The species is related to Plagiochasma Wrightii Sulliv., which 
shows the following differing characteristics : stomata not so much 
elevated, the 5—8 cells around the pore being in 2 or 3 concentric 
series ; appendicula not so much constricted, narrower, margins 
_ always entire ; peduncle shorter, 2-4 mm.(?); scales of the car- 
pocephalum never constricted ; spore distinctly tetrahedral and 
winged, exospore not so loose. Type duplicate of P. Wrightii 
from Texas in Herbarium Underwood shows 5-8 cells around 
pore instead of 6 cells as given by Herr Stephani in his Species 
Hepaticarum. 
These two Jamaican species differ from each other in shape and 
size of stomata, form of ventral scales and their appendicula, the 
Position of androecium and in the character of the cuticle. 
The above work was done under the supervision of Dr. Mar- 
: shall A. Howe to whom I am deeply grateful. Thanks are also 
due Professors Underwood and Evans for allowing me to study 
their material. 
New York BoranIca. GARDEN. 
Explanation of plates 5 and 6 
PLATE 5. Aytonia Evansii sp. nov. 
Tand 2. Plant, natural size. 
3- Outline of cross-section of thallus, <9 
4. Median cross-section of thallus showing stomata, X 55. 
5. Stoma, < 242. 
6, Plant, showing two immature carpocephala and androecium, X 6. 
7. Plant, showing nearly mature carpocephalum, with peduncle 4mm. long, and 
androecium, <6 
8 and 9. Ventral scales, X 13. 
to. Ventral scale showing geminate appendicula, X 13. 
TI-13. Scales from the carpocephalum, 13. 
14. Scale from the carpocephalum showing cells, X 55 
15. Surface view of stoma ; epidermal cells and trigones, 360. 
o. 
20. Elater, 2-spiral, 175. 
*1. Oil-body completely filling cell, X 250. 
22. Scale from androecium, 55. 
