188 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Sporangia at the base of filaments, which form scattered external 

 tufts -*. - Stilophora. 



38. Fronds minute, ending in a hyaline hair, monosiphonous below, 



densely beset above with very short branches, between which are 



the sporangia Myriotrlch ia. 



Fronds ending in a large, single cell, the cells of the lower part 

 giving off descending filaments, which become interwoven and 

 form a false cortex 39 



39. Ehizoidal filaments few and limited to the base of the plant, branch- 



ing, irregularly pinnate Sphacelaria. 



Ehizoidal filaments numerous 40 



40. Branches distichously pinnate Chcctopteris. 



Branches whorled Cladostephus. 



41. Fronds simple or occasionally proliferous 42 



Fronds branching 47 



42. Midrib present 43 



Midrib wanting 44 



43. Fronds stipitate, perforated with numerous holes Agarum. 



Fronds entire, with a few separate leaflets on the stipe below the 



lamina Alaria. 



44. Fronds thin, subsessile 45 



Fronds thick and coriaceous, distinctly stipitate 46 



45. Sporangia densely covering the surface of frond Phyllitis. 



Sporangia external in scattered spots Punctaria. 



46. Cryptostomata present, fronds attached by short, nearly simple 



rhizoids Saccorh Una. 



Cryptostomata wanting, fronds attached by prominent, branching 

 rhizoids Laminaria. 



47. Fronds without distinction of midrib and lamina, fruit borne on 



short lateral branches Ascophyllum. 



Blade distinct from the midrib, bladders borne in the laminae, 



fruit terminal Fucus. 



Bladders and fruit borne on special stalks Sargassiim. 



48. Fronds calcareous 49 



Fronds not calcareous .' 50 



49. Fronds erect, filiform, articulated Corallina. 



Fronds thin, horizontally expanded Melobesia. 



Fronds thick, horizontally expanded, but rising at intervals in 



irregular protuberances Lithothamn ion. 



50. Fronds horizontally expanded, crustaceous or membranaceous.. 51 

 Fronds erect or umbilicate . 52 



51. Fronds parenchymatous, spores in external warts Peyssonnelia. 



Fronds parenchymatous, spores in cavities sunk in the 



frond Hildenbrancltia. 



