164 p. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



This species is probably akin to Nav. Moiinionthianu Grln., and its p!ace here is somewhat 

 doubtful. 



17. C. amphioxys KiiTZ. (1H44) Grun. — V. almost symmetrical, narrow linear-lanceolate, 

 with sxibrostrate ends. L. 0,o"; B. (),oo7 mm. Median line almost central, straight. Axial area 

 narrow; central area indistinct. Strite 17 in 0,oi mm. slightly radiate in the middle and slightly 

 convergent in the ends, not distinctly punctate. — Narlc. cimp/iio.ri/f> KiJTZ. Bac. ]). 91 PI. XXVlll 

 1'. 37? Cynih. navic. var. amphioyx (Irun. in CI. M. I). N:o 273 (187II). 



Fresh water: Degernas, Westerbotten, Sweden, fossil! 



This form, frequent in CI. M. D. N:o 273, seems not to be akin to C. iiaticulacea. but rather 

 to the group of Naviciila radiosa, having, like those, the terminal strite convergent. 



18. C. acuta A. S. (18<S1). — V. almost symmetrical, lanceolate, with acute ends. L. 0,05 

 to 0,085; B. 0,0 ifi to 0,02 mm. Median line almost central, straight. Axial area narrow, linear, 

 in the middle dilated to a rhomboid-orbicular central ai'ea. Stritc 9 to II in 0,oi mm., very Hnely 

 punctate. — C. americana var. acuta A. S. Atl. LXXl f. 7.5 to 78. 



Fresh water: Sweden (Lake Rosslangen in Calniar Lan)! Mouth of Jenissey! Demerara Kiver! 



19. C. acntinscilla Cl. N. Sp. — V. slightly asymmetrical, lanceolate, gradually tapering 

 from the middle to the acute ends. L. 0,o7 to 0,09.5; B. 0,02 to 0,022 mm. Axial area narrow, 

 lanceolate, not (or on the ventral side slightly) dilated around the central nodule. Stri?e 9 to 10 

 (middle) or 11 (ends) in n,oi mm., slightly radiate in the middle, parallel at the ends, (;oarsely 

 pun<'tate; puncta 17 to 20 in 0,oi mm. - PI. IV f. 26. 



Fresh water: Crane Pond! Walthara, Mass.! 



This species is nearly akin to C. acnta, but has broader area and more coarsely punctate strirt^. 



20. €. Haiickii V. H. (1888). — V. asymmetrical-lanceolate, with arcuate dorsal margin, 

 slightly convex ventral margin and obtuse, not rostrate ends. L. 0,o7 to 0,o8; B. <>,oi8 to 0,02 

 mm. Median line slightly asymmetrical, almost .straight. Axial area narrow, lanceolate, scarcely 

 dilated on the dorsal, but distinctly on the ventral side of the central nodule. Stria' 10 (middle) 

 to 18 (ends) in 0,oi mm., radiate throughout, coarsely punctate; puncta about 18 in 0,oi mm. — 

 V. H. in Hauck and Richter Phycoth. univ. N:o U7. Notarisia 1888 p. (522. Icon. n. PI. IV f. 24. 



Fresh water: Triest! 



The above description is from original specimens in Van Heurck's collection. C. Haiickii is 

 similar to C. acutiiiscula, but the stripe are radiate in the ends, where they are much closer than 

 in the middle. C. Liuihaijana Grev. (Trans. Bot. Soc. Edinb. Vol. Vlll p. 234 PI. Ill f. 5 to 8) 

 has the same size and outline as C. Hauckii, but, according to Greville, somewhat coarser strijs. 

 The description and figures given by Greville are not sufficient for identification. 



21 . C. ainphicephala Naegeli (1849). — V. slightly asymmetrical, with ai^cuate dorsal and 

 almost straight ventral margin. Ends rostrate to rostrate-capitate. L. 0,o25 to 0,04; B. 0,00;) to 

 0,01 mm. Median line slightly excentric, almost straight. Axial and central areas indistinct. 

 Stria^ 12 or 14 (dorsal) to 16 (ventral) in 0,oi mm., more distant in the middle than elsewhere, 

 slightly radiate. — NAE(i. in Ktitz. Sp. Alg. p. 890. A. S. Atl. IX f. 62, 64 to 66; LXXI f. 52. 

 V. H. Syn. p. 61 PI. II f. 6. C. navicidiforniis Heib. Consp. Crit. p. 108 PI. I f. 2. 



Fresh water: Spitsbergen! Iceland! Sweden (Areskutan, Upsala, Billingen, Gulf of Bothnia)! 

 Denmark! Holstein! England! Saxony! Belgium (V. H.), Switzerland! Ispahan (Atl.), Tasmania! 

 New Zealand! Brazil! 



Var. subundulafu Cl. — V. linear, with slightly triundulate margins and capitate ends. 

 L. 0,04; B. 0,007 mm. Stri;e in the middle 16, at the ends 18 in 0,oi mm. 



Fresh water: Norway, Dovre! 



