1919- Bullock-Webster. — A new Nitella. 3 



Oospora 475-500 /x longa, 425-450 /a lata, 330 ^t crassa, 

 7 strias tenues exhibens alis promulis versus apicem. Mem- 

 branula rubra aut rubra-fulva, spissa, semi-rigida et trans- 

 lucens, scabra perpusillis tubercuWs, et minimis granulis 

 decorata. 



Antheridiiim 575-675 /x diametro. 



N. spanioclema is closety allied to N. flexilis, being 

 monoecious with branchlets normally once furcate, and 

 the ultimate ra3^s one-celled ; its fruit also is very similar. 

 It differs, however, from that species in its fragile and 

 delicate habit, the extraordinary paucity and irregular 

 development of its branchlets and secondary rays, and in 

 its occasional second furcation. When, as often happens, 

 the secondar}'^ rays are suppressed or only rudimentary the 

 antheridia have the appearance of being borne on long 

 stalks. In the frequent absence of lateral secondary rays 

 the plant bears a resemblance to A^. monodactyla Braun, a 

 sub-tropical dioecious plant described and figured in his 

 Fragmente. The oogonia are frequently produced at the 

 base of the whorls, and their enveloping cells are divergent 

 and much distended at the apex. The membrane shows the 

 peculiar mottled surface with w^art-like protuberances which 

 are characteristic of A^. opaca and N . flexilis, but besides 

 this it possesses a delicate decoration which is absent in 

 those two species. This decoration consists of exceeding 

 minute granules which are at first linear in their arrange- 

 ment, but at a later stage assume a reticular form. 



It will be interesting to ascertain whether the plant 

 occurs in other parts of Ireland. In the Fanad Peninsula 

 it appears to be confined to Lough Shannagh. 



Explanation of Plate I. 



I, 2. Plant natural size. 



3, 4. Branches with branchlets showing short solitary and rudimentary 



secondary rays and conspicuous scars left by fallen antheridia 



and oogonia, x 10, 



5. Oogonium, x 30. 



6. Oospore, showing ridges with broad flanges, x 30. 



7. Piece of membrane showing wart-like protuberances and minute 



granular decoration, x c. 200. 



8. Piece of raembrane showing disposition of granules, x c 800. 



a2 



