Ser. MELANOSPERME^. ( 103 ) Fam. DICTYOTEiE. 



LITOSIPHON PUSILLUS.— -ffam 



Gkn. Char. — Frond unbranched, cylindrical and cartilaginous, subsolid, at lengtb 

 tubular, composed of several rows of cells ; tbe surface areolated. Fructification : 

 solitary or aggregated naked spores, scattered irregularly over the surface of tbe 

 frond. Name from Ai'tos, "slender or mean," and (r'upov, "a tube" {Phyc. Brit.). 



LiTOSiPHON pusillm. — Fronds caespitose, slender, and filiform, cylindri- 

 cal ; surface reticulated, and clothed with pellucid hair-like filaments, 

 " spores scattered." 



LiTOSiPHON pusillus. — Harv. P. B. plate 270 ; Harv. Man. p. 43 ; Harv. Syn. 

 p. 38; Atlas, plate 13, fig. 52. 



Chlorosiphon pusillus. — Harv. m Phyc. Brit. vol. i, p. 10 (in list of species) ; 

 Kiltz. Sp. Alg. p. 484. 



AsPEROCOCCUS pusillus. — Carm. in Hooh. Br. Ft. vol. ii. p. 277 ; Wyatf, Alg. 

 Damn. No. 58 ; Harv. in MacJc. Fl. Hih. part 3, p. 175 ; Harv. Man. 

 1st edit. p. 35 ; /. G. Agardh, Sp. Gen. Alg. vol. i. p. 78. 



Hab. — Tajmsitical on Chorda Jllum. Annual. Summer. Very common everywhere. 



Geogr. Dist. — Shores of Europe. 



Description. — Fronds densely csespitose, covering the whole surface 

 of the plant affected with it with a dense wool-like covering, often for 

 a considerable extent, generally from two to three inches in length, and 

 scarcely thicker than a stout hair, cylindrical, filifonn, the siu'face at 

 first covered with abundance of minute, pellucid, jointed hairs scattered 

 over the surface ; as it advances to maturity these gradually disappear, 

 the surface becomes smooth, but less lubricous, and less adhesive. 

 Structure cellular, at first quite solid, at length hollow by the decay 

 of the internal parts ; the inner cells being partly empty and larger, 

 irregularly hexagonal, those near the surface filled with olive brown 

 endochrome. Substance very soft and lubricous, especially when yoimg, 

 and closely adhering to paper. Colour, a pale olive brown. " The 

 surface, under the microscope, appears reticulated with quadrate cells, 

 which are disposed in longitudinal lines. Among these cells one is here 

 and there larger and more prominent than the rest, containing a darker 

 coloured endochrome ; these are supposed to be the spores, and no other 

 fructification has yet been observed." 



A frequent parasite on old fronds of Chorda filum, which it often 

 covers for a considei'able extent, giving it the appearance of a bottle- 



