126 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



Dermocarpa violacea Crouan 



Tilden 1910, p. 53, pi. 3, figs. 19-21. 



Plants ovoid to pyriform, up to 20 [j. long and 30 /x broad, one celled, 

 forming a continuous layer on rocks, shells, etc., the cell contents dividing 

 into several or many rounded or angular cells which remain for some time 

 within the wall of the mother cell. 



Costa Rica: with Entophysalis granulosa Kiitz. on turret shells 

 along shore. Port Parker near Ba. Salinas, no. 39-88, 25 Mar. 1939. 



Stigonemataceae 



MASTIGOCOLEUS Lagerheim ex Bornet & Flahault, 1887 

 Mastigocoleus testarum Bornet & Flahault 



Tilden 1910, p. 237, pi. 14, fig. 12; Taylor 1928, p. 49, pi. 2, fig. 2. 



Plants discoloring shells dirty or yellowish green in shallow marine 

 situations, the much-branched filaments growing at the surface of the 

 shell and penetrating the outer layers, the spherical heterocysts borne 

 terminally on short branches. 



Mexico: Oaxaca, in old shells, in the lagoon at Ba. Chacahua, no. 

 39-72, 21 Mar. 1939. Panama: in old shells from tide pools in rocky 

 tidal flats, San Francisco, Panama, no. 39-149, 31 Mar. 1939. 



Rivulariaceae 



GALOTHRIX C. Agardh ex Bornet & Flahault, 1886 



Calothrix pilosa Harvey ex Bornet & Flahault 



Drouetl936, p.21,fig. 17. 



Mexico: Nayarit, on rock faces in heavy surf, I. Maria Magdalena, 

 Las Tres Marias, no. 39-673, 9 May 1939. Ecuador: I. Isabela, I. 

 Fernandina; also on twigs and roots in a lagoon, Pta. Albemarle, I. Isa- 

 bela, no. 34-94A, 12 Jan. 1934. 



ISAGTIS Thuret ex Bornet & Flahault, 1886 

 Isactis plana Thuret ex Bornet & Flahault 



Tildenl910,p.281,pl. 19,fig. 5. 



Plant a bright or dark blue-green cushion (up to several cm in 

 diameter and 1 mm thick), often coalesced with other plants and forming 

 a continuous stratum, on rocks, wood, shells, and larger plants between or 

 just below tidemarks, the filaments upright and parallel, the sheaths hya- 

 line becoming brownish, the inner portions distinct, the outer portions 

 diffluent and coalesced. 



