381 
I found them cruciately divided (or better perpendic- 
ularly divided). The tetrasporangiferous bands which 
contain one or a small number of sporangia are consi- 
derably swollen (figs. 322). In a tetrasporangiferous 
specimen a few sori of paraspores were observed, 
developed from superficial cortical cells (fig. 323). C. 
vertebrale occurs in 5,5 to 15 meters’ depth. It has only 
been recorded from localities around Bornholm and 
from one locality at the boundary between the Sound 
and the Baltic Sea. Fig. 323. 
Ceramium vertebrale. Zone with aheap 
Localities. Bm: RH, at Knollen west of Saltholm. — Bb: of paraspores. From a dried spec- 
SN, Davids Grund, 15—17 m; SL, off Allinge; SO, off Gudhjem; RUE EN M URI 
SK, Hojbratterne; SH, South of Broens Rev; YF, within Arnager ee as al i 
Rev; SF, Adler Grund. — (The locality Nyborg Havn recorded by 
Dr. Petersen (1908 p. 64) must be omitted, the specimens being now referred by Dr. Petersen to C. 
strictum f. radiculosa). 
7. Ceramium danieum Henn. Petersen n. sp. 
C. Rosenvingii H. Petersen f. tenuis et f. intermedia H. Petersen 1908, pp. 66, 90, pl. II figs. 5, 6. 
Frons dichotoma, apicibus incurvatis teretibus, in partibus superioribus et 
intermediis zonis discretis, in partibus inferioribus cortice continuo instructa. Zonæ 
juveniles marginibus non crescentibus, adultiores ab utroque margine crescunt ut 
in C. Rosenvingü. Interstitia pellucida interdum zonis 5—7-plo longiora. — Cysto- 
carpia in ramis primariis. — Color subruber. — Individua minus corticata habitum 
Cer. stricti offerunt. 
Ceramium Rosenvingü as described by me in 1908, comprises partly forms with 
feebly developed cortex, with the habit of C. diaphanum and C. strictum, partly forms 
with somewhat more developed cortex and finally forms approaching to C. rubrum. 
As such a variation must be considered too great, even when taking the species in a 
wide sense, I have found it correct to divide the species into two. It would perhaps 
be most correct to distinguish three species corresponding to the three forms which 
were described in 1908; however, I am not satisfied whether there is so distinct a 
limit between f. tenuis and f. intermedia that they ought to be regarded as distinct 
species. On the other hand f. transgrediens is so distinct from the two just named forms 
that it seems warranted to draw a specific limit between them. I describe therefore 
a new species comprising the forms fenuis and intermedia, while the name C. Rosen- 
vingii is retained for the f. transgrediens. 
C. danicum comprises forms with continuous cortex at the base or reaching a 
little over the middle of the frond and with the habit of C. diaphanum or C. strictum 
in the upper parts of the frond, while C. Rosenvingii comprises more robust forms 
with continuous cortex reaching to the apex or near the apex, with rubroid branches 
and without any habit of C. strictum. HENN. PETERSEN. 
D. K. D, Vidensk. Selsk. Skr., 7. Række, naturvidensk. og mathem. Afd. VII. 3. 49 
