452 NOTES AND MEMORANDA. 



row also divide. The innermost of the cells thus formed, together 

 with the adjoining cells of the flat portion, then further divide by 

 walls j)arallel to the j^lane of the latter, and thus form the cushion. 

 The marginal cells of the original row become, in Aneimia, the 

 " apical edge " of the cushion, growing in a direction at right angles 

 to the margin, but maintaining their narrow form. In Mohria no 

 such apical edge is formed. 



9. Both in Aneimia and Mohria the cushion is formed at the side 

 of the prothallium, rarely, in the former genus, at its apex. 



10. A common characteristic of the pruthallium of both genera is 

 the occurrence of papillfe ; in Aneimia only on the margin, and curved 

 towards the ajncal edge of the cushion ; in Mohria caffrorum, on the 

 contrary, almost exclusively on the surface of the prothallium. The 

 first papilla is always formed in close proximity to the lateral row of 

 cells. 



11. The rhizoids make their appearance on the oldest cells of the 

 germinal filament, and next most abundantly on the lower margin of 

 the prothallium, and especially on the same side as the row of cells 

 already mentioned. Subsequently, as in other cases, they spread over 

 the lower sm-face of the cushion. 



12. The antheridia are distinguished, in both genera, by the 

 formation of a bell-shaiied membrane when the central cell is sepa- 

 rated from the wall. The " stigmatic " or covering cell appears to be 

 always thrown off in Mohria caffrorum, while in Aneimia it is ruptured 

 in the form of a star. The first antheridia are produced in both 

 genera, like the rhizoids, on the margin below the lateral row of 

 cells, spreading thence to the surface of the cushion. 



13. The construction of the archegonia offers no striking pecu- 

 liarity. In Aneimia the neck was usually found straight ; in Mohria, 

 curved towards the base of the prothallium. 



14. From the time when the cushion is formed, the divisions 

 parallel to the surface of the prothallium continue in a backward 

 direction ; while the part which takes no share in the formation of the 

 cushion continues its marginal growth, and in Aneimia becomes more 

 and more arched upwards. 



15. In those prothallia of Aneimia where, from deficiency of 

 antherozoids or any other cause, fertilization is not effected, the 

 cushion always projects laterally in the form of an outgrowth of 

 usually nearly uniform breadth, and continues to grow at the apical 

 edge until either fertilization takes place or the prothallium perishes. 



16. Under certain unfavourable conditions the production of arche- 

 gonia on the cushion ceases, the cushion continuing its growth ; and 

 its lower side then becomes covered instead with antheridia ; thus 

 showing that the continued growth of the cushion need not necessarily 

 result in the formation of archegonia. 



17. While in the PolypodiaccfB and Cyatheacefe there are not 

 usually any adventitious shoots on the normally cordate prothallium, 

 such shoots are almost invariably formed, in both Aneimia and 

 Mohria, on the cushion of older prothallia, originating in cells belong- 

 ing to the flat portion. 



