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IK Lille Middelgrund, 17—19 m, 61 cm; IH, south side of Lille Middelgrund, 20—28 m; ER, Fyrbanken 
east of Anholt, 23 m, 28 cm; IA, Store Middelgrund, 16,5 m; same locality (Bergesen); off Gilleleje, 12 
miles from land (Lyngbye); Nakkehoved (Lyngbye). — Su: Washed ashore at Hellebæk (Rasch, Børgesen), 
29 cm, and north of Helsinger (Steenberg, C. Rosenberg, !) 26 cm, bM, south of Hveen, 22,5 m, loose, 40 cm. 
Fam. 5. Nemastomatacee. 
Platoma (Schousboe) Schmitz. 
1. Platoma Bairdii (Farlow) Kuckuck. 
P. Kuckuck, Beiträge zur Kenntn. d. Meeresalgen. 12. Ueber Platoma Bairdii (Farl.) Keck. — Wissensch. 
Meeresuntersuch. Neue Folge. V. Bd. Abt. Helgoland, Heft 3. 1912, p. 187—203. Taf. IX—XI. 
Nemastoma (?) Bairdii Farlow, Proceed. Amer. Acad. Arts and Sciences, 1875, p. 351; Mar. Algæ of New 
England, 1881, p. 142; Batrers, Cat. Brit. Mar. Alg.. 1902, p. 94. 
Helminthocladia Hudsoni Batters, Journ. of Bot. 1900, p. 377. Tab. 414 fig. 15 —16, non J. Agardh. 
In July 1915 I found by dredging in Lille Belt some small specimens of this 
interesting Alga, hitherto only recorded from three widely remote places (coast of 
Massachusetts, coast of Northumberland and Helgoland). As the structure and de- 
velopment of the species have recently been exhaustively treated by Prof. Kuckuck, 
I shall only make some few remarks upon the Danish specimens, referring for the 
rest to Kuckuck’s excellent description. 
The plant forms small bundles on a granitic pebble, each given off from a 
well developed basal disc, and reaching only a length of 1cm. The upright fronds 
are more or less branched, rarely unbranched, terete, or the thickest fronds some- 
what flattened. As shown by Kuckuck, the frond branches by dichotomy‘, but one 
of the shoots produced by the division often becomes more vigorous than the other, 
and the ramification then seems to be lateral. Hyaline hairs were not met with; 
according to Kuckuck their occurrence is variable. | 
The plants bore either tetrasporangia or carpogonia and cystocarps, while 
antheridia were not met with either here or at Helgoland. The two kinds of indivi- 
duals were quite distinct; no carpogonia were observed in the tetrasporiferous speci- 
mens or vice versa (comp. Kuckuck |. c. p. 192). The emptied sporangia were fre- 
quently replaced by a sporangium produced from the subjacent cell. “Prospory” 
2: production of sporangia from the basal dise, was not met with in the Danish 
specimens. 
Locality. Lh: At Lyngs Odde, right opposite Middelfart, stony bottom, about 20 meters depth. 
= Kuckuck thinks (I. c. p. 190) that the dichotomy in this plant is only apparent, as it cannot be 
derived from a longitudinal division of the apical cell. This, however, must be considered a too nar- 
row definition of the conception of dichotomy. In my opinion, dichotomy exists in all cases where 
the growing point divides into two equal parts by a vertical dividing plane or furrow, the two parts 
at first diverging equally from the original direction of growth, no matter whether the growing point 
consists of a single cell (Diciyofa) or of several cells (Furcellaria, Lycopodium, Selaginella, roots of 
Isoëtes etc.) or is a part of a coenocytic organism (Thamnidium, Piptocephalis). 
