274 NEMATOGEN.T-:. 



GENUS 112. HAPALOSIPHON. Nay. (18'.>.) 



Trichomes formed mostly of a single row of cells, sheath 

 slender. Aquatic plants, looking like Tolypotlirix. 



Hapalosiphon byssoideus. Kirch. Al<j. SchL, 231. 



Tufts compact, dark olive, trichomes ascending, rigid, oliva- 

 ceous, sparsely branched, containing cells arranged in a single 

 series. Cells at first rounded quadrate, equal in length and 

 breadth, becoming when older divided and shorter, one-third or 

 one-fourth the length of their diameter ; sheath very thick, 

 distinctly lamellose, golden yellow, attenuated and obtuse at the 

 apex. 



SIZE. Trichomes -025--03 rum. diam. Cells -012 x "01 

 mm. 



SirosipTion truncicola, Babh. Alg. Ear. ii., 286. Hedwigia 

 i., p. 47, t. ix., f. 3. 



Hassaliia byssoidea, Hass. Alg. 232, t. 67, f. 5. 



Scytoneuut byssoideum, Harv. Eng. Fl. v., 360. Berk. Glean., 

 t. 19, f. 1. Harv. Man. 156. 



On trunks of beech, &c. 

 J'latc CXI. fig. 5. Portions of trichomes X 400 diam. 



SPECIES FOR EN (I UIR Y. 



Dasygloia amorpha. Thwaites. 



Gelatinous, amorphous, sheaths of the trichomes thick, muci- 

 laginous, cohering, slightly branched ; internal trichomes blue- 

 green, slender, simple, septate. 



SIZE. Not indicated. 



Dasi/gloia amorpha, Thwaites in Eng. Bot. ii. Supp., t. 

 2941. " 



In bogs. 



Coalescing in a solid gelatinous mass, as large as a swan's egg. The 

 filaments, quite at the base of the plant, have rather a membranous 

 than gelatinous sheath, and closely resemble those of a Lynykya, in 

 consequence of which the base of the mass is green, but in the centre of 

 the plant each filament is furnished with a very thick colourless gela- 

 tinous sheath, which is firmly coherent with those in contact with it. 

 Towards the periphery of the plant these sheaths assume a brown 

 colour, and become somewhat separate and distinct, rendering the sur- 

 face shaggy. Occasionally the tips of the filaments are wound spirally 

 round the portion beneath them. 



Plate CXII. fg. 1. , portion of gelatinous mass, natural size; J, 

 threads, with gelatinous sheaths, magnified ; c, portion of trichome, with- 

 out sheath, further magnified all after Thwaites. 



