Myxonema 195 



Although one may be very sure of the distinctness of species, 

 it is a very difficult matter to construct a good key. It is hoped 

 that the following may be of some assistance, though it is very far 

 from satisfactory. 



Synopsis of Species 



Forms in which opposite branching predominates. 



Filaments 11-30/z in diameter, branches often approximate. 



Lower cells 1-2 times as long as broad, walls thickened, branchlets usually 



short-pointed. I. M. lubricum. 



Lower cells 2-5 times as long as broad, walls not thickened, branchlets more 

 attenuate. lb. M. lubricum varians. 



Lower cells 3-8 times as long as broad, branchlets pointed. 



2. M. amoenum. 

 Lower cells 4-8 times as long as broad, branchlets setiferous. 



3 . M. flagellifet um . 

 Lower cells scarcely longer than broad, branchlets thorn-like, acute. 



4. M. subuligerum. 

 Lower cells 2-5 times as long as broad, much inflated. 



5. M. ventricosnm. 

 Filaments 7-1 0/1 in diameter, branches less crowded, transitional form. 



Lower cells 1-3 times as long as broad, branchlets tapering or setiferous. 



6. M. tenue. 

 Forms in which alternate branching predominates. 



Filaments short, cespitose. 



Growing in thermal waters ; diameter 7.5-12 fx. 7. M. the)- male. 

 Growing in water of ordinary temperature. 



Diameter 6-8 /z, branchlets obtuse or short-pointed. 



8. M. nanum. 

 Diameter 7-9//, branchlets erect, attenuate or setiferous. 



9. M. aestivale. 

 Diameter Ii-i4.fi, branchlets densely fasciculate, setiferous. 



10. M. glomeratum. 

 Filaments more or less elongated. 



Diameter 5-7 fi. 11. M. attenuatum. 



Diameter 8-1 1 fi. 12. M. stagnatile. 



Diameter 12-18 fi. 13. M. sub secundum. 



i. Myxonema lubricum (Dillw.) Fries, Syst. Orb. Veg. 343. 



1825; Flora Scan. 329. 1835. 



Conferva lubrica Dillw. Brit. Conferv. pi. 57. 1 March, 

 1806. Agardh, Syn. Alg. Scand. 92. 18 17. (?) Lyngb. Tent. 

 Hyd. Dan. 150. pi. 32. 18 19. Not C. lubrica Roth. Cat. 

 Bot. 3 : 168. 1806 \==Tetraspor a lubrica~\. 



Drapamaldia tenuis elongata Agardh, Syst. Alg. 57. 

 1824. 



