KONGL. SV. VKT. AKADEMIRN8 HANDUNGAR. HAND 27. N:() 3. ^f) 



Nnr. rctnso Br^b. seems to be a form, akin to N^ov. cancellata, and therefore entirely dif- 

 ferent from this species, which I have, with much hesitation, placed in Pinnularia. 



Var. {Amphora) Digitus A. S. (1875). — V. asymmetrical. L. 0,05 to 0,i; B. O.oo: to 0,0 12 

 mm. Axial area asymmetrical, a little broader on the dorsal side. Stria; 8 in 0,01 mm., not dis- 

 tinctly punctate. Frustnle rectangular. Connecting zone with several faint longitudinal divisions, 

 which are finely transversely lineate; lineola; 24 in 0,oi mm. — Amphora Dif/itus A. S. Atl. XXVI 

 f. 30. Cl. and Grove Diatomiste I p. fi7 PI. X f. 11 to 13. 



Marine: North Sea! Guernsey (Grove Coll.)! Balearic Islands! Macassar Straits! China! 



71. P. bistriata Leud. Fortm. (1879). — V. linear; with rounded ends. L. 0.055 to O.oc.r. ; 

 B. 0,009 mm. C-entral nodule transversely dilated. Axial area narrow; central area a broad, trans- 

 verse fascia. StriiK 10 in 0,01 mm. radiate in the middle, transverse or convergent at the ends. 

 — Stauroncis histriata Leud. Fortm. D. (!eylon PI. IX f. 89. 



Marine: Mediterranean Sea (Barcelona)! Ceylon (Leud. Fortm.). Labuan ! 

 I have seen only two valves of this characteristic; form and I have jilaced it in Pinnularia 

 with great hesitation. 



72. P. quadratarea A. S. (1874). — V. narrow, linear, with parallel margins and broad 

 rounded extremities. L. 0,oi to 0,09; B. 0,oii mm. Median line with small terminal fissures. 

 Axial area indistinct or very narrow; central area a broad fascia. Stria; parallel, 8 to 10 in 0,oi 

 mm. — Nav. Pinnularia Cl. (1868) Sv. N. D. p. 224 PI. IV f. 1. 2. Nar. quadrat. A. S. N. S. D. 

 p. 90 PI. II f. 2fi. 



Marine: Arctic Seas (Arctic America. Spitsbergen, Finmark, Novaja Zembla, (Jape Wanka- 

 rema)! North Sea (Bohuslan, Sweden)! Mediterr. (Balearic Islands)! Australia Sydney! 



This species was first described by me as Nai-\ Pinnularia, and later by A. Schmidt as Nav. 

 quadratarea, but as my specific name would be inadmissible I have given preference to the name 

 of A. Schmidt. It is a very variable species, of which a great number of forms has been described 

 as distinct species, but as they are closely connected I have united them. The chief distinction 

 consists in the outline and the number of striae. Closel}' connected with some of the varieties (Var. 

 flmnincnsit etc.) are P. floridana Cl. and P. cruciata. On the other hand the var. Thcclii approaches 

 to P. craciformis Donk. The varieties may be arranged in the following series. 



A. Forms with linear, not constricted valves. 



Var. haltica Grun. (1880). — B. 0,oo8. Strise 9 in 0,oi mm. — Nav. Pinn. var. halt. 

 Grun. a. D. p. 27. 



Brackish water: Baltic (Grun.). 



Var. Seychellensis Grun. (1880). — V. short, linear, with rounded ends. B. 0,ou mm. 

 StricE 12 in 0,oi mm. — Nav. Pinn. var. Seych. Grun. A. D. p. 2S. 



Marine: Seychelles (Grun.). 



Var. Soderlnndii Cl. (1880). — V. linear, with rounded ends. L. 0,036 to 0,o4.'j; B. O.ooq 

 to 0,00 7 mm. Strite 13 to 1(5 in 0,oi mm. — Nav. Pinn. var. Soderl. Cl. A. D. p. 28. 



Marine: Davis Strait! Balearic Islands! Tahiti! 



Var. Tahitensis Grun. (1880). — V. linear, with subcuneate ends. B. 0,oo9 mm. Strite 13 

 in 0,01 mm. — Nav. Pinn. var. Tah. Grun. A. D. p. 28. 



Marine: Tahiti (Grun.). 



Var. interrupta Cl. (1883). — V. linear, with subcuneate ends. L. 0,08; B. 0,o2 mm. 

 Strife 9 in 0,oi mm., crossed by irregular, longitudinal, blank bands. — Nav. Pinn. var. interr. 

 Cl. Vega p. 4«J3 PI. XXXVI f. 21. 



Marine: ('ape Wankarema! 



