90 COLLINS AND HERVEY. 



regularly dichotomous throughout, the axils rather wide and rounded, 

 the divisions immediately incurving and often becoming parallel, the 

 apices rounded. Antheridia of the usual form were found on these 

 plants; also, on the same plants, scattered or in twos, tetrasporangia; 

 none of these were found showing the regular division into fours, but 

 in many the contents had divided into many small squarish cells, the 

 sporangium enlarging to two or three times its former dimensions, 

 and developing a point of growth at the tip. This closely parallels 

 the development in D. dichotovia, described and figured by Reinke, 

 1878, p. 8, PI. I, figs. 31-35. The occurrence on the same frond with 

 antheridia is, however, noteworthy. We hardly see how I), voluhilis 

 Vickers, Algues de la Barbade, No. 78a, can be distinguished from the 

 present species, apart from the spiral twisting of the frond. A plant 

 in the Kemp herbarium, marked D. fasciola, is intermediate between 

 D. indica and D. voluhilis of the Algues de la Barbade. 



4. D. CERVicoRNis Kiitzing, 1859, p. 11, PI. XXIV, fig. II; D. 

 fasciola Harvey, 1852, p. 108, PI. VIII. B., not of Lamouroux. Rein, 

 as D. fasciola. The true D. fasciola has slender fronds, regularly but 

 not very closely dichotomous, the divisions all developing equally and 

 ending at nearly the same level. In D. cervicornis one division is 

 frequently short, acute and erect, giving quite a different habit, which 

 is well characterized by the specific name. 



5. D. Bartayresii ^^ Lamouroux, 1809, p. 331; D. Bartayresiana, 

 Harvey, 1852, p. 110, PI. VIII. C; P. B.-A., No. 1874. Kemp, as D. 

 fasciola, in part; in shallow water, Moseley; St. David's Island, from 

 half tide down, April, Shelly Bay, May, Gravelly Bay, Hungry Bay, 

 July, Cooper's Island, Aug., Collins; Gibbet Island, Jan., Oct., Dec, 

 Hervey. This seems to be the species of Dictyota occurring most 

 frequently in Bermuda. It is quite variable, and narrow forms cer- 

 tainly show similarity to D. divaricata. On comparing the accounts 

 given of the species by different authors, and the specimens from dif- 

 ferent localities distributed under this name, one is led to suspect that 

 more than one species is really in question. As originally described, 

 stress was laid on the acute apices, but later authors include forms with 

 distinctly blunt apices. Both forms occur among the Bermuda 

 material we have studied. It is probable that all species of the genus 



11 This species is generally known as D. Bartayresiana, but in the original 

 publication by Lamouroux the specific name is Bartayresii. Few authors 

 refer to this rare and neglected paper, almost all starting from a later publi- 

 cation of the same year, 1809a, p. 43, in which the author, without stating 

 any reason, substitutes the name Bartayresiana. 



