KONGL. SV. VET. AKADEMIENS HANDLlNOAIi. HAND 18. N:0 5. 15 



Length 0,088 0,109 imii. Breadth 0,0080,00!) mm. 



PI. Ill, Hg. 4(i, ^""7,. 

 Ralearie Islets rare (F. Sodehlund). 



Among the Stauroneis forms, known to me, there are two, which have a similar 

 structure: St. Stodderi Lewis and 5/. Stodderi vai-. innupiis Gkun., both freshwater spe- 

 cies. St. sulcata is marine and has finer striae. 



3. Stauroneis Africana Cl. N. S]i. 



Valve very convex, hyaline, elongate. Stauros reaching the margins. Stria' hue, 

 23 in 0,01 mm., parallel, reaching the median line. 



Length 0,05 mm. Breadth 0,01 mm. 

 PI. Ill, fig. 42, ^""V,, a. F.V., b. S.V. 



Fresh, or very slightly brackish water, Zwathrops River, Port Elisabeth, South 

 Africa in a sample sent by Mr. W. Joshua (Cl. and Moll. Diat. N:o 196). 



This form is nearly related to 6\ salina W. Sm., but has finer striae. The stria? 

 of S. salina are 17 in 0,01 mm. 



4. Stauroneis pachycephala Cl. N. Sp. 



Linear, gibbous in the middle and at the ends, which are broadly rounded and 

 capitate. Strite oblique, very fine, about 29 in 0,01 mm., reaching the median line. 

 Stauros reaching the margin. Median line straight. Terminal nodules turned in oppo- 

 site direction. 



Length 0,055 mm. Breadth 0,009 mm. 

 PI. Ill, fig. 43, '7,- 



Fresh or slightly brackish water, Baakens River, Port Elizabeth, Soutli Africa in 

 a sample sent by Mr. Joshua (Cl. et MOll. N:o 197). 



This species comes nearest to St. desiderata Cl. (in Cl. et Grun. Arctische Diat. 

 PL III, fig. 58), which also has the terminal nodules turned in opposite direction, but 

 the outline of this species is different and its striae are almost parallel and much 

 coarser. Both belong to a section parallel with Grunows section Pseudopleurosigma 

 of Navicula. 



5. Stauroneis {Pleurostauron) Sagitta Cl. N. S[). 



Elongated, apiculate, to the outline resembling St. Smithii Grun. Ends with short 

 interior diaphrams as in Pleurostauron. Stria; oblique 21 in 0,01 mm. one or two in 

 the middle very strong. 



Length 0,030,04 mm. Breadtli 0,0060,01 mm. 

 PL III, fig. 45, '">'!,. 



Fresh water, mouth of Tana Elf, Finmarken, collected bj' Prof. Th. M. Fries 

 (Cl. et Moll. Diat. N:o 261 not rare). 



