XL OBSERVATIONS ON GIGARTINA. 



MARY E. OLSON. 



The genus Gigartina is of wide distribution, especially in 

 temperate latitudes. It is found both in the Atlantic and Pa- 

 cific oceans as far north as the coast of Greenland and as far 

 south as Cape Horn. 



The material used in preparing this paper was collected 

 in Puget Sound, at Channel Rocks, near Seattle, Washington, 

 on August 3, 1897. It does not correspond exactly with any of 

 the specific descriptions recorded. Indeed it has been with 

 some reluctance that this plant has been included in Gigartina. 



The material used for study in the preparation of this paper 

 had been preserved in 75 per cent, alcohol, with the exception 

 of some dried material which was studied in determining the 

 color, size, shape and other external characters. 



In the dried material the fronds appear thin and membrana- 

 ceous and very brittle. The alcoholic material is leathery in 

 texture and quite tough. The older fronds show a considerable 

 increase in thickness over the younger ones, and are strongly 

 Calltblepharis-\\\iQ. in appearance. 



HABIT AND EXTERNAL APPEARANCE. 



The fronds are reddish purple in color and occur at a depth 

 of eight fathoms. Several or more fronds are generally found 

 growing crowded together from united holdfasts. Such a group 

 is seen in Fig. i, PI. 13. 



The general outline of a frond whether branched or un- 

 branched is typically cuneate. Fig. 3, PI. 13 shows a good 

 specimen of the unbranched type. When branched the general 

 wedge-shaped outline is retained by a more or less regular, 

 dichotomous form of branching, in which the branches spread 

 and remain of considerable width. (Fig. i, PL 13.) 



