NITELLA SPANIOCLEMA. 109 



broad, 330 /x thick, rich red-brown, showing six 

 thin ridges with prominent flanges towards the apex ; 

 outer membrane thick and semi-rigid, translucent, 

 bright red-brown, scabrous often with small protu- 

 berances, decorated with very minute granulation 

 somewhat reticulate in form (PI. IV, figs. 5-9). Antlie- 

 ridiuin 575-675 p. in diameter. 



DISTRIBUTION.- -Ireland : Donegal, W. Lough Shan- 

 nagh (G. R. B.-W., 1916); Lough Kindrum (G. R. 

 B.-W., 1919). 



A medium-sized plant about 30-35 cm. in height, slender and 

 extremely delicate, dull olive green in colour. It is closely 

 allied to N. flexilis being anarthrodactylous, monoecious,, and 

 normally once furcate, but differs so much from that species 

 in its lax and delicate habit, the extraordinary paucity of 

 branchlets and secondary rays and its tendency to bifurcation 

 that it seems to demand specific rank. It would appear in 

 some respects to resemble the dioecious subtropical N. mono- 

 dactyla, Braun, judging from the particulars and figures in 

 the f Fragmente/ but of this we have not seen satisfactory 

 specimens. It will be seen from the illustrations that 

 N. spanioclema exhibits remarkable irregularities of growth 

 which if found in one individual would be regarded as due 

 to extreme abnormality, but the plant occurs in plenty and 

 the peculiarities are observable in every specimen, moreover 

 they persist from year to year. The normal number of 

 branches produced at a node in the genus Nitella (two) is 

 frequently exceeded while that of the branchlets falls always 

 far short of the usual number, six. An oogonium is often 

 produced at the base of a whorl as well as in the normal 

 position. The lateral rays are often so much reduced at a 

 node where an antheridium is present that the latter appears 

 to be seated on a long stalk. 



The plant occurs in some abundance in Lough Shannagh 

 and Lough Kindrum, in the Fanad Peninsula, West Donegal. 

 It was first collected by Gr. R. B.-W. in August, 1916, again in 

 August, 1917, and August, 1919. In Lough Shannagh it was 

 growing in dense masses in some 5-6 feet of water and fruiting 

 freely. Its extraordinarily delicate character may be gathered 

 from the fact that it became flaccid almost immediately after 

 removal from the water, and even when transferred to drying- 

 paper on the bank of the lake it was difficult to secure any 

 satisfactory specimens. 



