KONGL, SV. VET. AKA0EMIENS HANDLINGAR. BAND 26. N:0 2. 191 



^ J Axial area indistinct T Clepsydra Dokk. 



' \ — — linear, frequently unilateral 7. 



j Alveoli in regularly decussating rows T. Debyi Lbdd. Foetm. 



' \ — — irregularly — — T. Antillarum Cl. 



1. T. aspera Ehb. (1843). — V. elliptic- to linear-lanceolate or elongated rhomboid. L. 0,o6 

 to 0,3; B. 0,024 to 0,05 mm. Ends obtuse or rounded. Axial area very narrow or linear and 

 unilateral. Centi'al area a broad stauros, widened and truncate outwards. Alveoli forming trans- 

 verse striae, radiate throughout, 6 to 18 in 0,oi mm. in more or less oblique rows. 



Symmetrical forms. 



Var. genuina Cl. — V. linear-lanceolate, obtuse. L. 0,i5 to 0,2; B. 0,028 to 0,033 mm. 

 Alveoli close. Rows of alveoli 7 to 10 in 0,oi mm. Longitudinal fine striae distinct, 26 in 0,oi 

 mm. — Stauroptera aspera Ehb. Am. PI. I f. 1, 2. Nav. aspera V. H. Syn. PL X f. 13. Suppl. 

 B. f 26. A. S. Atl. XLVIII f. 15, 21, 22. Donk. B. D. PI. X f. 1. Nav. pseudo-aspera "Bant. UI 

 PI. XVni f. 258 (1893). 



Marine: North Sea! Singapore (Atl.), Amboina (Kinker Coll.)! Sydney! Japan, fossil (Brun 

 Coll.)! Mexillones guano (Deby Coll.)! 



Yar. vulgaris Cl. — V. elliptic- or linear-lanceolate. L. 0,n to 0,2; B. 0,02 to 0,o3 5 mm. 

 Axial area indistinct or very narrow. Alveoli close. Kows of alveoli about 10 in 0,oi mm. 

 Longitudinal fine striae about 25 in 0,oi mm. — Nav. aspera A. S. XLVIII f. 2 to 6. 



Marine: Arctic America! North Sea! Cape of Good Hope! New Zealand! Samoa! New Cale- 

 donia! Java! Galapagos Islands! 



Var. Neumeyeri Janicsh (1876). — V. large, lanceolate. L. 0,3; B. 0,o5 mm. Axial area 

 narrow. Hows of alveoli about 9 in 0,oi mm. — Nav. Neum. A. S. Atl. XLVIII f. 1. 



Marine: Cape Horn (Petit). 



Var. rohusta Petit (1877). — V. narrow, elliptical, with acute or subcuneate ends. L. 0,o9 

 to 0,14; B. 0,028 to 0,035 mm. convex, with a longitudinal depression on each side of the median 

 line. Axial area indistinct. Alveoli forming three longitudinal bands and somewhat radiate strife, 

 6 (middle) to 8 (ends) in 0,oi mm. — Stauroneis rohusta Petit D. de Campbell p. 27 PI. V f. 16. 



Marine: Campbell Island (Petit Coll.)! 



Var. angusta Cl. — V. narrow, linear-lanceolate. L. 0,12; B. 0,oi8 mm. Rows of alveoli 

 11 in 0,01 mm. 



Marine: Sumbava (Kinker CoU.)! Colon (Deby Coll.)! 



Var. contermina A. S. (1876). — V. narrow elliptical. L. 0,048; B. 0,on to 0,oi2 mm. 

 Axial area narrow. Striae in slightly radiate, transverse, rows, about 10 in 0,oi mm., crossed by 

 a few longitudinal blank bands. — Nav. contermina A. S. Atl. XLVIII f. 17, 18. 



Marine: Japan (Atl.), Cape Horn (Petit). 



Var. pulchella W. Sm. (1853). — V. narrow, elliptical, gradually tapering towards the obtuse 

 ends. L. 0,075 to 0,085; B. 0,oi5 to 0,02 mm. Axial area indistinct. Alveoli close, forming oblique, 

 and slightly radiate, transverse rows, 13 to 16 in 0,oi mm. — Stauroptera Achnanthes Ehb. Am. 

 p. 135 PI. IlL 3 f. 7? M. Geol. XVII: 1 f 10? Stauroneis pulchella W. Sm. B. D. I p. 61 PI. XIX 

 f. 194. Navicula aspera Donk. B. D. X f. 1 b. Stauroneis pygmcea Castr. Voyage Challenger 

 p. 25 PI. XXIX f. 7. A. S. Atl. XLVIII f. 12, 13 (no name). 



Marine: North Sea! Philippines! Samoa! Sandwich Islands! 



Var. residua A. S. (1876). — V. narrow, linear-lanceolate. L. 0,i; B. 0,012 mm. Axial 

 area indistinct. Rows of alveoli 18 in 0,oi mm. — Nav. residua A. S. Atl. XLVIII f. 29. 



Marine: Japan (Atl.), Cape Horn (Petit). 



