Howe: Phycological studies 499 



genus, germinate precociously or while still attached to the thallus, 

 so that the surface appears inconspicuously proliferous here and 

 there. 



The only Dictyotas hitherto recognized from the Pacific coast 

 of North America are, so far as we are aware, Dictyota crenidata 

 J. Ag. from St. Augustin, Mexico, and D. Binghamiae of California. 

 Of these, D. crenidata is characterized by strong marginal teeth, 

 which are wholly lacking in D. Vivesii; by elongate or lingulate, 

 broadly obtuse or subtruncate terminal segments, which are as 

 broad as any part of the thallus; by a cortex that is for the most 

 part conspicuously fenestrate in the Agardhian sense; by thicker- 

 walled cells; and by a usually reticulate surface when dry. 



Dictyota Binghamiae is a coarser, thicker (275-500^), more 

 regularly dichotomous plant, with segments usually broader and 

 their width better sustained towards the apices; its surface is 

 beautifully reticulate when dry, and under the microscope the 

 cortical cells, in most cases, show very clearly the differentiation 

 in form and translucency that suggested the term "fenestrate" 

 to J. Agardh. The cortex, too, of D. Binghamiae, towards the 

 margins and in the older parts, often shows two or more layers 

 of cells, — a character that is presumably responsible for its former 

 identification with Glossophora Kunthii. The walls of the interior 

 cells, that is, the walls that are perpendicular to the surface, are 

 very firm and thick (5-30/;). 



RHODOPHYCEAE 



Porphyra leucosticta Thuret in Le Jolis, Liste Alg. Mar. 



Cherbourg 100. 1863 



San Felipe Bay, D. T. MacDougal, Feb. 1904. 



This species, so far as we are aware, has hitherto been attrib- 

 uted, for the Pacific coast of America, only to Monterey Bay, 

 California.* The Gulf of California specimens differ a little in 

 color from most European and eastern American plants, tending 

 rather more to brownish and blue-purple shades. 



The thallus is about 40/x thick, surface jelly 8-1 i/x thick; plants 

 monoecious; antheridia in spots and streaks adjoining sporocarps, 



* Hus, H. T. A. Zoe 5: 63. 1900; Proc. California Acad. Sci. III. 2: 202. 

 1902. 



