ne 
This species comes near to C. atlanticum, C. Rosenvingt and C. rubriforme, from 
which it differs by cortical bands more resembling those in C. Areschougü, with cells 
arranged in characteristic rows in the lower part of the zones. In contradistinction 
to C. atlanticum the ramification is distinctly dichotomo-corymbose with slight form- 
ation of secondary shoots. The specimens from the Baltic Sea have formerly been 
referred to C. Rosenvingü f. transgrediens. (HENNING PETERSEN). 
In the Northern Kattegat it has been found with antheridia, cystocarps and 
tetrasporangia in June. The Danish specimens reach a length of 8,5 cm. 
Localities. Km: Several places in the neighbourhood of Frederikshavn, e. g. Degets Nordostrev. 
— Bw: KU, Schünheyders Pulle. 11m. — Bm: VH, Böchers Banke. 
14. Ceramium abyssale Henn. Petersen n. sp. 
C. rubrum f. decurrentoides Henn. Petersen 1908, pp. 82, 96. 
C. fronde dichotoma vel subdichotoma, apicibus excl. juvenilibus = rectis, cortice 
continuo vel zonis juxappositis difficile distinguendis instructa. Zonz discrete solo- 
modo in basibus ramorum occurrunt, typo C. fruticulosi vel C. Areschougii, in mar- 
ginibus superioribus magis quam in inferioribus crescentes. Cystocarpia in ramis 
principalibus vel secundariis. Tetrasporangia verticillata vel sparsa parum erumpentia. 
Color subruber. Hab. in regione abyssale. 
On closer examination of the specimens which in 1908 were referred to C. rubrum 
f. decurrentoides I have found that these specimens, owing to the structure of the 
cortication, must rather be considered as related to C. fruticulosum than as a form 
of C. rubrum. It differs from C. fruticulosum in particular by the presence of distinct 
bands at the base of the branches. HENNING PETERSEN. 
C. abyssale has only been met with in considerable depths, (8,5—31 m) in water 
of high salinity. It has been collected only in summer (July, August), with cystocarps 
and tetraspores; it reaches a length of 11,5 cm. 
Localities. Ns: aF, Jydske Rev, 31 m. — Sk: ZK", off Lønstrup, 8,5 m; off Hirshals, 15 m. — 
Kn: FG, Herthas Flak, 21 m. — Ke: VY, Fladen, 18 m. 
15. Ceramium Areschougii Kylin. 
Kylin 1907, p. 179, Taf. 7 Fig. 6; Henn. Petersen 1908 p. 69, Figs. VI, 1 and VII, 2, 1911 p. 100 Fig. II. 
The species has only been met with in summer, May to August, most frequently 
in June and July. It seems to thrive best in the inner western waters where it 
reaches a length of 15—16 cm. It has been found with tetraspores in May to 
August, with cystocarps in June and July, and both modes of fructification occur 
in all the waters where the species has been met with. It grows in all the waters 
in various depths from 1/2 m to 15 m; in the Little Belt it has once been found in 
a depth of 19 m or deeper. 
