421 
the specimens of P. elongata agree with the typical form in all respects. Spec- 
imens from the Kattegat collected in 17—19 meters’ depth were certainly a little 
slenderer than those from higher levels and usually showed longer joints, 1—3 times 
as long as broad, but the branches tapered downwards and the trichoblasts were 
branched. 
P. elongata occurs in all the Danish waters and also enters in the fjords. It 
descends to 20 meters’ depth but has been recorded in 27 meters’ depth in the 
eastern Kattegat and in 24,5 meters’ depth near Bornholm (f. baltica). It grows on 
various substrata, stones, moles, shells of mollusks, various Algæ, as Fucus serratus, 
Laminaria digitata, etc. and Zostera. It occurs in very different plant associations 
but usually not as a dominant constituent. In oozy bottom it is frequently met 
with on mollusk shells. It is remarkable that it may occur rather abundantly in 
places where the flora is poor in species, f. inst. Fano and Logstor. It often attains 
a length of 23 cm, more rarely 35 cm, but only in protected localities. In autumn 
many specimens die but others are only denudated and recommence the growth in 
winter. New shoots may appear already at the end of December, and in January 
they are usually present though the growth is slow. Thus, new shoots more than 
one cm long were found in a specimen gathered on January 25th in the Great Belt; 
but it must be said that other specimens gathered in other localities in the same 
water were still in a resting stage. The growth is intense in April and May, it con- 
tinues in June and July but in the latter month it decreases and usually ceases. 
The trichoblasts may remain still for some time, but in several specimens they 
are thrown off already in August. Otherwise this takes place in autumn, and at the 
same time a number of shoots, principally the fructiferous ones and the ends of 
the shoots are shed. 
Antheridia were met with in January (unripe), April, May and July, and once 
even in August, ripe cystocarps in May to September, most frequently in July and 
August, unripe in April and May, ripe sporangia in May to August. The sporelings 
arising from the spores disseminated in summer continue their development, after 
wintering, the next year; but it is doubtful whether they can winter more than once. 
Localities. «, typica. NS: Nordby, Fano; Esbjerg; Thyboron, harbour and groins; off Orhage, 
5,5—7,5 m. — Sk: YU, Hanstholm, 2 m; within Bragerne, 2—10 m; off Løkken, 13 m; Dana St. 2900, 
9m (C. A. J.); FK?, off Lønstrup; Hirshals mole and off Hirshals, 2—11 m; Højen, within first and 
, second shoals, 2—5 m. — Lf: LV, Nissum Bredning; MH, Thisted Bredning; Oddesund; Nykobing (Th. 
Mortensen, !); four localities east of Mors; north of Fur, Lendrup Ron, Logstor, Aggersund (Ostenfeld). 
— Kn: Skagen; fC, S. of Skagen, 15 m; FG, Herthas Flak; off Hulsig (Boye Pet.); Krageskoys Rey (KC 
and TV); Hirsholmene; Fladstrand (Hornemann); harbour of Frederikshavn and reefs off Frederikshayn, 
off Marens Rev, 20 m; harbour of Sæby; BP, off Sæby; Nordre Renner; TL, NG, VT, fF, UC, UB, GM, 
north of Læso; harbour of Osterby; TO (17 m), TP, TQ, NI, FF, FE, fG, Dana St. 3891, near Trindelen. 
— Ke: FC, FD, XA, east of Læsø; VY, ZE, fH, Fladen; Groves Flak, down to 26,5 m; IK, ET, Lille 
Middelgrund; HX, Store Middelgrund, 17 m; GI, Ostindiefarer Grund; OO, Soborghoved Grund; Gille- 
leje, Nakkehoved (Lyngbye). — Km: Læsø Rende; Dana St. 2619, 2884 (C. A. J.); YY, XD, XF south 
of Læsø; BN; TS; VQ, Svitringen; BM; BL; VP; bK, N.W. of Anholt, 15 m; BK, VM, near Tangen; 
NC; BI, Gjerrild Flak; Gjerrild bay (Lyngbye). — Ks: EP, Pakhusbugt, Anholt; OP, HQ, EJ, Lysegrund; 
D. K. D. Vidensk. Selsk., 7. Række, naturvidensk. og mathem. Afd. VII. 3. 54 
