THE GREEN ALGAE OF NORTH AMERICA 293 



ovoid, up to to 30 p. diaiii., containing numerous spores. In 

 fronds of Ralfsia Borneti Kuckuck. Me. to Conn. 



4. P. REINSCHII (Wille) Collins, 1908, p. 125 ; Acroblaste sp. 

 Reinsch, 1879, p. 365, PI. III. A. Basal layer of monosi- 

 phonous filaments, with rounded cells about as long as broad ; 

 vertical filaments about ^2 mm. high, 5-8 /u diam., cells about 

 twice as long as broad, cylindrical or slightly constricted at the 

 nodes ; sporangia ovoid, 16-20X20-25 ^ ; terminal or apparently 

 lateral on the erect filaments. On shells and pebbles. Mass. 



In this species the basal layer shows the filamentous character 

 throughout, even when the filaments are laterally united ; often 

 they remain practically free. The color is a yellowish, some- 

 what olivaceous green ; it has some resemblance to a small 

 species of Ectocarpus. It is often mixed with Micro chaete grisea 

 Thuret, Calothrix species, and other small algae. 



5. P. RIMOSA Kiitzing, 1843, p. 273 ; 1854, p. 20, PI. XC. ; 

 P. B.-A., No. 971. Forming a dense, yellowish green stratum; 

 basal layer of somewhat irregular cells, more or less torulose ; 

 erect filaments reaching a height of 2 mm., simple or branched, 

 cylindrical or torulose, cells 7-10 /u diam., length of cell, 1-2 

 diam. ; reproduction unknown. On woodwork near high water 

 mark. Me. Europe. 



Forms a very compact coating, that can be removed in pieces 

 of considerable size ; Calothrix pnhnnata grew with it at the 

 Maine locality, nearer low water mark ; the stratum was con- 

 tinuous, Calothrix below, Pilinia above, the two mixed for a 

 space in the middle. 



6. P. MORSEI Collins, 1908, p. 126, PI. LXXVII, figs. 4-6. 

 Basal filaments irregularly contorted, more or less united ; cells 

 rounded, 8-15/0. diam., often divided longitudinally and forming 

 a subparenchymatous membrane of two or more layers ; erect 

 filaments up to 2 mm. high, 7-11 /u diam:, cells 1-2 diam. long, 

 cylindrical or slightly moniliform ; sporangia ovoid or pyriform, 

 on the basal la) r er, sessile or on a few-celled pedicel. Fig. 90. 

 On woodwork, N. J. 



Showing more differentiation than the preceding species, 

 assimilative and fertile growths being both distinct from the 

 basal layer. 



7. P. MARITIMA (Kjellm.) Rosenvinge, 1893, p. 933, fig. 43 ; 

 Chaetophora maritinia Kjellman, 1877, p. 51, PI. IV, figs. 15 

 and 16. Frond subspherical, 1-3 mm. diam., basal layer not 



