74 



with numerous shells of Balanidæ, Serpula and other animals. 

 Sometimes it is intersected in the middle, or even assuming a more 

 or less whorl-shaped appearence. PL 12, fig. 2. 



There is a considerable difference between younger individuals, 

 or such branched from the centre of the frond, spherical or hemi- 

 spherical, and old ones with the lower branch-systems disappeared, 

 depressed cup-shaped or sometimes nearly flattened. In the former 

 the branches are more or less bent, or even somewhat contorted, 

 especially in the lower part not or only a little, but in the upper 

 part always more or less anastomosing. In the latter the axes 

 are very short, always much anastomosing, and even the upper- 

 most part of the branches in old specimens often somewhat denu- 

 dated. The branches are 2 mm. in diameter, or less, sometimes 

 in the part of not opened specimens turned towards the bottom 

 slightly attenuating, with rounded or obtuse ends (pl. 12, fig. 1), 

 and in the part turned upwards either cylindrical, here and there 

 bearing short branch-like or wart-like processes, or, more frequently, 

 slightly enlarged apex, or towards the apex, more regularly fasti- 

 giate than in the lower part, and the ends as a rule obtuse, more 

 seldom nearly truncate, the latter also being due to the upwards 

 turned part of old and cup-shaped specimens of f. typica. Pl. 11. 



In the form grandifrons the uppermost branches form minute 

 and rather densely crowded bundles, composed of very short, more 

 or less anastomosing branches and wart-like processes. Pl. 13, 

 fig. 1 — 2. These branches are often rather thin, sometimes even 

 but 1 mm., the bundles occasionally rather depressed, or in part 

 denudated, with wart-like processes issuing from the denudated and 

 often more or less truncate bundles. Cp. Pl. 13, fig. 3, seen from 

 the side that has turned towards the bottom. In the part that has 

 turned upwards it is rather rubbed and the branches somewhat 

 coarser, here and there denudated. Of this form I only have seen 

 old or rather old specimens. It appears, as if the named bundles 

 are not unfrequently developed from an older and somewhat denu- 

 dated frond, rather reminding one of the new branches developed 

 from the lower and rubbed part of other specimens. It is in its 

 typical form rather characteristic, but on the other hand apparently 



