KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 18. N:0 5. 15 



Length 0,088—0,109 mm. Breadth 0,008—0,009 inra. 



Pl. III, %. 46, '""'/,. 

 Balearic Islets rare (F. Söderlund). 



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

 structure: St. Stodderi Lewis and St. Stodderi var. insignis Grun., both freshwater spe- 

 cies. *S(. sulcata is marine and has liner stria3. 



3. Stauroneis Africana Cl. N. Sp. 



Valve very convex, hyaline, elongate. Stauros reaching the margins. Stria3 fine, 

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



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

 Pl. III, fig. 42, ^"""A, a. F.V., h. S. V. 



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

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



This form is nearly related to »S. salina W. Sm., but has finer striaä. The striag 

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



4. Stauroneis pachyceijhala Cl. N. Sp. 



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

 capitate. Striaj 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. 

 Pl. III, fig. 43, ""7,. 



Fresh or slightly brackish water, Baakens River, Port Elizabeth, South 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 striaä are almost parallel and inuch 

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

 of Navicula. 



5. Stauroneis (Pleurostauron) Sagitta Cl. N. Sp. 



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

 interiör diaphrams as in Pleurostauron. Strife oblique 21 in 0,01 mm. one or two in 

 the middle very strong. 



Length 0,03—0,04 mm. Breadth 0,006—0,01 mm. 

 Pl. III, fig. 45, ^""Vi. 



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

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



