KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 



27. 



n:o 



195 



10. A. baccata Lbud. Fortm. (1879). — Linear, with broacl, rounded ends. L. U,i; B. 0,o25 

 mm. Lower V. with wide and irregular axial area. Central area large and irregularly transverse. 

 StricB 7 in O.o i mm. formed of large puncta, arranged in iindulating, longitudinal rows. — Staiiro- 

 neis baccata Leud. D. de Ceylan p. 37 Pl. III f. 35. Ächnanthes curvata Leud. 1. c. Pl. I f. 5? 

 A. bacc. Icon. n. Pl. III f. 3. 



Marine: Colombo, Ceylon (Le Tourneur CoU.)! 



11. A. groenlandica Cl. (1873). — Linear with rounded ends. L. 0,u4 to 0,ob; B. 0,oo5 

 to 0,007 mm. Upper V. with narrow axial area and strong costate stritB, 4,5 to 6 in 0,oi mm. 

 crossed by a longitudinal line. Lower V. with indistinct axial area. Central area a broad trans- 

 verse fascia. Central pores of the median line somewhat distant. StritB 5 to 6 in O, o i mm. 

 slightly radiate, formed by 3 to 4 large, distant puncta. Frustule genuflexed. Connecting zone 

 with a row of puncta, 6 to 7 in 0,oi mm. Lower valve with rudimentary diaphragms. — Ach- 

 namhidium groenlandicum Cl. A. D. p. 25 Pl. IV f. 23. Ächnanthes yr. GtRUN. A. D. p. 20. 

 Cl. Vega p. 460 Pl. XXXV f. 3. 



Marine: Arctic America! Greenland! Spitsbergen! Finmark! Behrings Island! 



12. A. creimlata Grun. (1880). — Elliptical to elliptic-linear, obtuse, with crenulated 

 margin (2,5 to 3 undulations in 0,oi mm.). L. 0,o34 to 0,o7 6; B. 0,oi5 to 0,02 mm. Upper V. 

 with very excentric and narrow axial area. Strise parallel, 6 to 6,5 in 0,oi mm. coarsely punc- 

 tate; puncta 6 to 7 in 0,oi mm. Lower V. with narrow but distinct axial area. Central area a 

 transverse fascia. Stria; 6 to 7 in 0,oi mm. slightly radiate throughout, punctate; puncta ti to 7 

 in 0,0 1 mm. — A. D. p. 20. Cl. Diatomiste I p. 50 Pl. IX f. 3, 4. 



Fresh or brackish water: New Guinea! Samoa! Australia (Daintree River)! 



Ächnanthes Bory S:t Vincent (1822). 



Outline linear to elliptical or lanceolate. Upper valve with central and narrow axial area, 

 without central nodule and median line. Lower valve with median line and stauroid central 

 nodule. Axial area narrow. Structure similar in both 

 valves: transverse costtB, alternating with double rows 

 of small puncta, arranged in decussating rows. Frus- 

 tule genuflexed, stipitate. No annulus. Connecting 

 zone transversely striate. The cell-contents of A. lon- 

 r/ipes have a number of scattered, rounded or elongated 

 chromatophore-gr anules . 



Ächnanthes, limited as above, has a great resem- 

 blance to Achnanthklium, as regards the manner of 

 living and the form of the frustule and the valves, but 

 the structure is difFerent. Of the affinities of Ächnan- 

 thes little can be stated. The structure of A. javanica 

 and of A. bengalensis, which, according to Grunow, have 

 longitudinal lines, has some resemblance to that of 



Scoliotropis and Gomphoneis. Mastogloia Grevillei has a similar structure, but differs greatly in 

 other respects. There is also some resemblance to Mastoneis, the central nodule of which also 

 forms a stauros, although short. 



1. A. longipes C. Ag. (1832). — Lineai'-elliptical, with broad, rounded and frequently 

 cuneate ends, usually slightly constricted in the middle. L. 0,oo5 to 0,i8; B. 0,oi2 to 0,027 mm. 

 Upper V. couvex. Axial area a central, linear silicious rib. Costfe 7 to 8 in 0,oi mm. parallel, 



Ächnmithes longipes with cell-contents: 500 times 

 niagnified. 



