— 98 — 



a more extensive examination and as the preserved material has 

 not given further informations on this point, the matter must rest 

 with this hint. 



Cerain. diaphanum (auct.) Harvey & Agardh and Cerara. strictum 



Grev. Fig. I; plate I, figs. 2 and 3. 



The algologists seem to agree in the view that C. diaphanum 

 and C. strictum are two far related species ; on the other hand one 

 cannot find much certainty according to the limits of these species; 

 we scarcely understand of which opinion Roth, Lightfootand Greville 

 have been. 



If it should be demonstrated by examination of the original 

 specimens of these species that C. strictum is described on the base 

 af a strictoid form of diaphanum, Fosiie and Woronichin would 

 be perfectly right in their opinon of C. strictum as a variety of C. 

 diaphanum. But in this case the specimens referred by me to C. 

 strictum should be to refer to a new species. For the fact is 

 that these specimina are distinctly separated from C. diaphanum 

 (Comp, the figs. 2 and 3 on plate I where respectively a strictoid 

 C. diaphanum and a typical C. strictum (sensu meo) are shown). 

 When we investigate typical specimens of C. diaphanum and of 

 the supposed C. strictum *), it is easy to indicate the differences 

 which exist between these. As indicated in my paper (1908) these 

 differences appear in the height of the zones — in the distances 

 of these and last but not least in the character of the bark. The 

 bark of the typical C. diaphanum consists of numerous small bark- 

 cells stretched lengthwise (cf. my paper 1908, Fig. IV, 4), while on 

 the other hand the bark of the C. strictum is formed by greater 

 cells few in number (1908, Fig. IV, 2) (Fig. I, 2). When we now 

 investigate the cells in the lower margin of the zones of these species 

 we observe that the cells in C. strictum (Fig. I, 3) often possess a 

 great diameter across (c. 17 — 20//) while the same cells in C. dia- 

 phanum never are more than 13^ broad (Fig. 1, 1). All the specimens 

 with character of C. strictum (Fig. I, 1 & 4) (plate I, fig. 2) situated 

 in morphological respect between the two species always show 

 cells of the C. diaphanum-type, never of that of C. strictum, in 

 other words the difficult specimens are always to be regarded as 

 forms of C. diaphanum with reduced bark. The opinion that they 

 might be forms of C. strictum with more divided bark is not prob- 



I have examined dried specimens from Denmark in Dr. Kolderup Rosen- 

 vinges and my own collections. 



