I 0LLIN8 \\D 111 RVE1 . 



of which we have examined several specimens, belongs under IK 

 citiata, Agardh, L848, p. 94, Bays of D. orenulata "margine tenui 

 dentibua brevissimis late triangularibus initio fere serrate, demum 

 dentato aul crenato." Harvey. 1852, Bays "The margin is undulated, 

 and closely eroso-denticulate, or jagged with unequal, deltoid or subu- 

 late, tooth-like processes.' 1 In the Bermuda plants the margin is 

 quite even, and the teeth are of uniform size and never very closely 

 set We have, however, seen a specimen of D. crenvlata from the 

 Suhr herbarium "West [ndien," that fully agrees with Agardh'a 

 and Harvey's descriptions. In the Bermuda material of this spt 

 confervoid rhizoidal filament- arise from the lower part of the main 

 axis of the frond, often forming a dense, continuous ma era] 



em.; proliferations are few and insignificant Antheridia and OOgonia 

 were found on specimens collected in February, tetra-poranuia on 

 specimens collected in July. 



8. I>. DENTATA I.amonronx. 1809, p. 331; Kutzing, 1859, p. 15, 

 PI. XXXV, fig. I: J). Mertensii (Mart) Kutring, L859, p. 15, PL 

 XXXVI, fig. I; Uha Mertensii Martius, L826, p. 21; L827, PL I; 

 P, \\. -A.. No. L926; IK BrongniartiiJ. (i. Agardh, L841, p. 5; Kutaang, 

 1859, p. 15, PL XXXV, fig. II; 1). svbdentata Kiitzinf:, 1859, p. 14, 

 PL XXXIII, f i <_r . II. Kemp, as D. crenvlata, in part; Gravelly Bay, 

 •Ian., Hervey, Aug., Collins; Hungry Bay, July, Collins. J. G. 

 rdh, L880, p. 98, gives I). Mertensii as a synonym of D. lirong- 

 niartii, mentioning D. subdentata without expressing an opinion as to 

 whether it should he referred to 1). dentata or D. Brongniartii; later, 

 1894, p. 70, he recognizes IK dentata, IK Mertensii and J). Brongniartii 

 a> distinct species. Hauck, L888, p. 466, unites all four under the 

 oldest name. I), dentata, as it seems to ns rightly. The distinctive 

 characters are found in the greater or less distinctness of the axis and 

 branches, and in the character of the terminal segments. In the 

 abundant material we found in Bermuda, there were individuals with 

 the primary axis narrower and firmer than the lateral segments, and 

 others, apparently mostly younger Individuals, in which all was 

 uniformly membranaceous. Typical I), dentata has segments ending 

 in acute, spinous tip-; typical I). Mertensii ha- segments -hort- 



CUneate, with truncate or emar-inate tips. It is not uncommon to 



find both these type- on the same individual. In comparing the 

 tative structure of I), dentata with that of I), dichotoma, a- de- 

 scribed by Eteinke, 1878, several point- are to be noted. The main 

 axis i- thick, and somewhat flattened, but can hardly he described as 



a " rundtriel)." In old plants, there -row from this, for a distance of 



