124 COLLINS AND HERVEY. 



4. P. FEETTLACEA Suhr in J. G. Agardh, 1863, p. 980; P. B.-A., 

 No. 1940; P. bremarticulata Harvey, 1853, p. 36, PI. XVI. B, not of 

 J. Ag. Rein, as P. nigrescens in part; Moseley, as P. svhtilissima; 

 Spanish Point, Harrington Sound, Jan., Gravelly Bay, Feb., April, 

 Tucker's Town, Feb., Dec., Hervey. A rather common and generally 

 distributed species. Harvey's figure represents the plant quite ac- 

 curately, except as to the quadrangular section of the filaments, 

 which was probably due to the use of dried material; the Bermuda 

 material shows the usual circular section. Rhizoids are well devel- 

 oped on the lower, prostrate part, arising each from a pericentral cell, 

 often one from each segment. Where the creeping filament is near 

 to a firm substratum, the rhizoids are short and stout; where there is 

 no such stratum near, the rhizoids may be much elongated, up to 

 3 mm. long, becoming very slender. In the actively growing tips, 

 the segments may have a length of only one fifth their diameter; 

 in older parts the segments may be slightly longer than their diameter; 

 the usual length is about one half a diam. Leaves are abundant, 

 branches being produced from their axils. 



At Heron Bay we found a plant agreeing quite closely with P. fracta 

 Harvey, 1853, p. 38, and with an authentic specimen in the Farlow 

 herbarium; it seems to us, however, to be only an old and battered 

 form of P. ferulacea. Authentic specimens of the latter, in the Farlow 

 herbarium, confirm this view. 



5. P. OPACA (Ag.) Zanardini, 1842, p. 165; P. B.-A., No. 1891; 

 Hutchinsia opaca Agardh, 1824, p. 148. Kemp, as P. fihrillosa; Rein, 

 as P nigrescens, in part; On rocks. Heron Bay, Jan., March, Ely's 

 Harbor, April, Hervey; in grotto, Tucker's Town, April, Fairyland, 

 Dec, Collins. We have included under this name all the many- 

 tubed Polysiphonias that we have found in Bermuda. Some speci- 

 mens agree well with the European form, others, specially those from 

 Fairyland, considerably resemble P. simulans Harvey, but we have 

 not been able to draw any line between these and the more typical 

 forms. Tetraspores were found in April. Branches arise in the axils 

 of the leaves. 



DiGENEA Agardh. 



D. SIMPLEX (Wulfen) Agardh, 1822, p. 389; Harvey, 1853, p. 29, 

 PI. XIII. D; P. B.-A., No. 1939; Conferva simplex Wulfen, 1803, p. 7. 

 Castle Harbor, Farlow; Gravelly Bay, Feb., Mangrove Bay, Feb., 

 Harris Bay, April, Dec, Hervey; St. David's Island, April, Collins. 

 Fairly common at various places, but plants usually small compared 

 with ordinary forms of Florida and the Mediterranean. 



