KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 63. N:0 8. 



33 



it is widely distinct. The smallest proliferation, such as illustrated in fig. 14 a, strongly 

 recalls the tip of a true Delesseria. But in tliis and allied genera the cells of the central 

 row never divide transversely, while, in Phycodrys and its allies, intercalary cross walls 

 appear early, and the cell thns cut off carries fewcelled lateral branchlets, inserted be- 

 tween the ordinary branches of 1. order (see below, fig. 15 c). In fig. 14 b, a marginal 

 tooth of Pseudophycodrys, the analysis is still easy enough, and here o n e intercalary 

 cross wall (i-i) is observed, and fig. 14 c of a growing apex presents a structure distinct 

 from that of D. sanguinea but also from Phycodrys. Still I believe that a type like 



Fig. 13. Pseudophycodrys phyllophora: tetrasporic specimen, nat. size. 



Pseudophycodrys may be derived from Delesseria or rather Membranoptera Stackh., be- 

 coming nitophylloid by intercalary divisions. The cells of the central region elongate 

 and form the costa, and lateral veins are developed in the same manner, directed to- 

 wards marginal top-cells: this formation of veins is, so to say, secondary, what explains 

 that they are not strictly opposite but quite as often alternate. 



The occurence of hyphae in costa and larger veins is a character of the Delesserieae 

 (fig. 14 d), never found in the Phycodrys or Nitophyllum assemblage. The young lamina 

 is monostromatic, gradually getting corticated. Mostly there is only a single layer of 

 cortex cells. 



The procarps are not formed on the veins, but often close to them, in which case 

 the wall of the cystocarp appears fused with the cortex of the vein. Or, a secondary 

 venule may be formed, joining the cystocarp with a vein. In any case, the costa or veins 



K. Sv. Vet. Akad. Handl. Band 63. N:o 8. 5 



