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



This species is probably akin to Nav. Monmouthiana GtRUN., and its place here is somewhat 

 doubtful. 



17. C. amphioxys KtJTZ. (1844) Geun. — V. almost symmetrical, narrow linear-lanceolate, 

 with subrostrate ends. L. 0,o7; B. 0,oo7 mm. Median line almost central, straight. Axial area 

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

 convergent in the ends, not distinctly punctate. — Nacic. amphioxys Kutz. Bac. p. 91 PI. XXVIII 

 f. 37? Gymh. navic. var. amphioyx GtKun. in CI. M. D. N:o 273 (1879). 



Fresh water: Degernas, Westerbotten, Sweden, fossil! 



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

 to the group of Navicula radiosa, having, like those, the terminal strise convergent. 



18. C. acnta A. S. (1881). — V. almost symmetrical, lanceolate, with acute ends. L. 0,o5 

 to 0,085; B. 0,016 to 0,02 mm. Median line almost central, straight. Axial area narrow, linear, 

 in the middle dilated to a rhomboid-orbicular central area. Striae 9 to 11 in 0,oi mm., very finely 

 punctate. — C. americana var. acuta A. S. Atl. LXXI f. 75 to 78. 



Fresh water: Sweden (Lake Rosslangen in Calmar Lan)! Mouth of Jenissey! Demerara Eiver! 



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

 from the middle to the acute ends. L. 0,07 to 0,095; B. 0,02 to 0,022 mm. Axial area narrow, 

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

 (middle) or 11 (ends) in 0,oi mm., slightly radiate in the middle, parallel at the ends, coarsely 

 punctate; puncta 17 to 20 in 0,oi mm. — PI. IV f. 26. 



Fresh water: Crane Pond! Waltham, Mass.! 



This species is nearly akin to C. acuta, but has broader area and more coarsely punctate striae. 



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

 slightly convex ventral margin and obtuse, not rostrate ends. L. 0,o7 to 0,0 8; B. 0,oi8 to 0,0 2 

 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. Striae 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 147. Notarisia 1888 p. 622. Icon. n. PI. IV f. 24. 



Fresh water: Triest! 



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

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

 in the middle. C. Lindsayana Grbv. (Trans. Bot. Soc. Edinb. Vol. VlII p. 234 PI. Ill f. 5 to 8) 

 has the same size and outline as C. HaucMi, but, according to Greville, somewhat coarser striae- 

 The description and figures given by Gteeville are not sufiicient for identification. 



21. C. aniphicephala Nabgbli (1849). — V. slightly asymmetrical, with arcuate dorsal and 

 almost straight ventral margin. Ends rostrate to rostrate-capitate. L. 0,025 to 0,o4; B. 0,oo9 to 

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

 Striae 12 or 14 (dorsal) to 16 (ventral) in 0,oi mm., more distan,t in the middle than elsewhere, 

 slightly radiate. — Naeg. in Kutz. Sp. Alg. p. 890. A. S. Atl. IX f. 62, 64 to 66; LXXI f. 52. 

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



Fresh water: Spitsbergen! Iceland! Sweden (Areskutan, Upsala, Billingen, Gulf 6f Bothnia)! 

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

 New Zealand! Brazil! 



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

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



Fresh water: Norway, Dovre! 



