28 HENRIK PRINTZ [1920 



gamietes escape. At times, however, there occur gametaiigies drawii 

 out iiuto a longeir or shorter bealv, with the opening at the end. (Vide 

 pi. VII, fig. 245 and pi. VIII, fig. 253 aaid 260). This is rare, however, 

 and must apparently be regarded as an abnormity. The chromato- 

 pliore in tliis species is often seen to contract in a characteristic way, 

 on accouiit of the desiccation. For the chromatophore is broadest at 

 the cross-walls of the cell, and narrows towards the middle, like an 

 hour-glass. PI. VIII, fig. 250 will give an idea of this. 



This species is very oommon in quite a number of the samples 

 examined from Durban, but I have not observed it in any of the 

 samples from Saklanha Bay. As to its occurrenoe may be noticed 

 that in practioally all the sampleis examined, it is associated 

 with a liver-wort and Phijsolinum monile (nos. 108, 120, 133, 179., 

 261, 295) or sometimes with Acanthococcus graniilatus var. 

 aerophilus (nos. 105 and 195). 



Trentepohlia umbrina (Kutz.) Bornet, in Wille, Algol. Mit- 

 theil. p. 42(3. [PI. IX and X, Fig. 264—289]. 



This species is of very common occurrence on the bark of trees 

 m several of the samples from the environs of Durban, but is 

 entirely lacking m the samples from Saklanha Bav (nos. 9, 37, 85, 

 108, 132, 133, 134, 153, 177, 179, 235, 248). 



The specimens drawn on the accompanying piates IX and X 

 aire all from sample 133. 



It will appear from the pictures of this widely distributed and 

 variable species that in the South-African specimens the cells 

 are usually more or less rounded, spheirical-ellipsoid or ovoid, al 

 times even ol a rather irregular shape. When young only, the cells 

 are nearly cylindric and about 3 — 4 times as long as broad, with 

 thinner walls, while the older ones, which are apt to be roimded off 

 and to undergoing disintegration, have a thicker membrane exhibit- 

 mg a distinct stratification. The membrane is ahvays hyaline. 

 These older thick-walled and isolated cells really aet, and must be 

 considered as the akinetes of the species. The ramification is very 

 irregular, and this species rarely forms distinct filaments. The 

 cells mostly lie in irregular rows in large heaps, frequentlj'- 

 in several layers. The size of the cells is very varying, from 

 quite small up to 35 fi in diameter. The average size is 15 — 25 //. 



The thicloiiess of the membrane is also very varying, 3 — 4 jn, at 

 times up to 7 ju. The gametangies do not differ very much from 

 the vegetative cells either in form or size. They may be terminal or 

 intercalar^\ The diameter of the gametes is about 4 k, and they 

 escape through a hole in the wall of the motlier cell. 



The specimens from South Africa agree on the whole very well 

 with the Scandinavian ones and with the material of this species 

 in Wittrock et Nordstedt, Algae Exsiccatae nos. 42,015, and 1423. 



