BY A. H. S. LUCAS. 177 



P o L Y s I P H o n t i a Greville. 



POLYSIPHONIA ZOSTEEICOLA, sp.nov. 



Fronds gregarious, forming a thick fringe to the leaves of 

 Zostera, not intricate, slender, to 2'5 cm. long. Attached by 

 small basal disc, branching below dichotomous, above more 

 pinnate. The branches come off at an angle of 45°, giving off, 

 at rather long intervals, other like but gradually slenderer branch- 

 lets, tin- last very slender and sometimes secund. Diameter of 

 main axis, 180//. Basal articnli lxl, of rami 2x1, of tetraspo- 

 rangiferous ramelli lxl. Four pericentral siphons. Substance 

 rather firm, the plants suffering prolonged immersion in water. 

 The frond adheres closely to paper when dry. Colour brownish, 

 purple, darker on drying. Tetrasporangia small, on but little 

 distorted ramelli. Cystocarps nearly sessile, ovate (326x258/*), 

 contracted at base. 



Frondes gregariae secundum margines foliorum zosterse dense 

 crescentes. Axis disco basali affixus, deorsum dichotomus, 

 sursum magis pinnatus, ramis ad angulum 45° emergentibus. 

 Hamuli distantiis longioribus similiter emergentes, ultimi non- 

 nunquam secundi. Axis primarius 180/* diam. Articuli in- 

 feriores lxl, ramorum 2x1, ramellorum tetrasporangiferorum 

 lxl. Siphones perieentrales 4. Substantia firma, haud celeriter 

 soluta: frons exsiccata urcte adheret. Tetrasporangia parva in 

 ramulis parum distortis. Cystocarpia fere sessilia, ovata (32G- 

 258/x) basi contracta. 



Growing abundantly on Zostera leaves in salt and in brackish 

 water, Botany and Middle Harbour, N. 8. Wales. 



This species seems to be near to P. amphibia Harv., from New 

 Zealand, which, how ever, I have not seen, and in which the 

 median articuli are described as nodose, and the axils its patent. 



T &ICHOD E S M I u M Ehr. 

 TRICHODBSMIUM SCOBOIDEUM, sp.nov. 



Pasciculis brevissimis ad "5 mm. longis, siccitate fuscis: tricho- 

 matibus rectis ad genicula baud constrictis, apice rotundatis haud 

 attenuatis, 9, 10/x crassis; articulis diametro trichomatis '.', plo- 



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