318 Pub. Paget Sound Biol. Sta. Vol, 2, No. 53 



the margins are throughout the whole length serrated with small spiniform, 

 rather remote teeth; the stem, from root to summit, is pinnated with op- 

 posite distichous branches^ of the same substance as itself, between hori- 

 zontal and patent, separated b}^ intervals of about half an inch, a foot or 

 a foot and a half long, and the middle ones apparently longest, their 

 greatest width nearl}^ an inch, attenuated at their bases into very short 

 subcylindrical petioli, rounded at their apices, toothed at their margins, 

 and in their turns pinnated with a series of others, similar to them in 

 every particular, except their small size; throughout the whole frond runs 

 a midrib thick and rather wide in the stem, but in the branches thin and 

 faint, so as scarcely to be visible, unless the plant is held to the light, and 

 appearing only like a dark line." 



He compares this new species with D. ligulata, setting forth very 

 clearly his reasons for considering it a distinct species. Postals and 

 Ruprecht (1840) also discuss the specific differences. J. G. Agardh, 

 (1848), however, placed D. herbacea as a variety under D. ligulata and 

 was followed by other systematists, including De Toni (1895) and Setchell 

 (1903). Harvey (1858 and 1862) went so far as to consider D. herbacea 

 merely a broad form of D. ligidata. Griinow (1867) again raised the 

 qxiestion of specific difference, supported by Skottsberg (1907); and the 

 writer (Pease 1917), in a preliminary paper, published D. herbacea as a 

 distinct species. In this discussion, however, all of the forms too broad to 

 be included with the typical D. ligtdata were considered as belonging to 

 the species D. herbacea (Turn.) Lamour. In the present paper the writer 

 Avishes to correct that statement, limiting the species D. herbacea to those 

 forms which correspond exactly with Turner's original description, and 

 setting apart the larger, broader forms in a group by themselves. 



As thus limited, the specimens distributed by Collins, Holden and 

 Setchell (1905), P.B.-A. 79 a. and b., under Desmarestia ligulata f. 

 herbacea, would belong here. 



During the summer of 1918 an abundance of material was collected, 

 which corresponds remarkably with Turner's description and plate. These 

 plants were collected in the same locality and at the same time as the 

 specimens of D. ligulata. No intermediate forms were found. The two 

 species were absolutely distinct. A glance at the mass of fronds as they 

 lay floating in the water was sufficient to identify the plant. In color, in 

 width of frond, and in texture, there was no possible room for doubt. 

 The same outstanding differences are manifest in formalin material and 

 herbarium specimens. Anyone who has seen the two plants together could 

 not possibly doubt their identity as distinct species. The two plants are 

 of about the same size. The writer has not collected a specimen of either 

 species which had attained a meter in length. D. ligulata is darker in 



