THE ALGAE OF BERMUDA. 47 



lents and smaller ramuli than C. piscinae. C. crystaUina, the most 

 nearly related Bermuda species, has larger main filaments, smaller 

 and more closely set ramuli, longer cells, more fasciculate habit, softer 

 substance, and does not become dark in drying. 



12. C. rigidula sp. nov. Filamentis primariis circa 120^ diam., 

 secundi ordinis 100 n, cellulis ultimis 80 ju; cellularum longitudine 

 diametrum 1-2-plo superante; nodis hand constrictis; cellula termi- 

 nali plerumque longiore, interdum ad 3 diam., rotundata vel subacuta; 

 ramificatione prope basin per dichotomias patentes, primo approxi- 

 matas, deinde distantes; ramis partis superioris frondis longis, rectis, 

 ramulos gerentibus fere vel omnino sub angulo recto egredientes, dis- 

 tantes sparsosque inferne, in seriebus secundis prope apicem; colore 

 viridi dilute obscuro; chromatophora subtiliter reticulata, pyrenoi- 

 deos multos, minutos, nitidos monstrante; substantia firma crispaque. 



Main filaments about 120 /u diam., secondary 100 /JL, ultimate cells 

 80 /j.; length of cells 1-2 diam., nodes not constricted; terminal cell 

 usually longer, sometimes 3 diam., rounded or subacute; branching 

 at base by broad forkings, at first frequent, later distant; branches 

 in upper half of frond long, straight, with ramuli nearly or quite at 

 right angles, distant and scattered below, near the tips in secund 

 series; color rather dull light green; chromatophore a fine network 

 with very many small bright pyrenoids; substance firm and crisp. 

 In a stone tank above the bridge at Fairyland, Dec. 13, 1915. Type 

 in Collins herbarium, No. 8513. 



Though occurring in a station similar to that of C. piscinae, and in 

 some points resembling the latter, it has seemed to us better to con- 

 sider it a distinct species than to combine the two by too vague a 

 description. C. piscinae, though crisp, promptly collapses when 

 taken from the water, C. rigidula long keeps its shape and stiffness; 

 the distinction is as marked as that between Polysiphonia molacea 

 and P. fastigiata. In C. piscinae the cells are seldom under three or 

 over five diam. long; in C. rigidula they are seldom over two diam., 

 often only one diam. for a good part of the frond; the terminal cell is, 

 however, often three diam. long. In both the ultimate ramuli are 

 patent, often at a right angle; in C. piscinae they are scattered and 

 usually distant, in C. rigidula closer and often in secund series. The 

 differences can hardly be due to the station, as each grew in a stone 

 tank, sea water going in and out with the tide, but with no active 

 current, and no disturbance of the surface. On the other hand it has 

 some resemblance to the plant from Harrington Sound which we 

 distributed, P. B.-A., No. 2014, as C. utriculosa, but is still further 



