164 P. T. CLEVE, SYNOPSIS OF THE XAVICULdll) DIATOMS. 



This species is probably akin to Nav. Moniiionthiana ItRUN., and its place here is somewhat 

 doubtful. 



17. C. ainphioxys Ktlxz. (1844) Grun. — V. almost symmetrical, narrow linear-lanceolate, 

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

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

 convergent in the ends, not distinctly pnnctate. — Nacic. uiiipliioxyn Kuxz. Bac. p. Dl Pl. XX^'111 

 f. 37? Cymh. naric. var. amphioyx (tRUN. in Cl. M. I). N:o 273 (187ft). 



Fresh water: Degernäs, Westerbotten, Sweden, fossil! 



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

 to the gronp of Nacicula radiosa, having, like those, the terminal strite convergent. 



18. C. acuta A. S. (1881). — V. almost symmetrical, lanceolate, with acnte ends. L. 0,u5 

 to 0,085; B. 0,0 J 6 to 0,02 mm. Median line almost central, straight. Axial area narrow, linear, 

 in the middle dilated to a rhomboid-orbicular central area. Strise 9 to 11 in O.iu mm., very finely 

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



Fresh water: Sweden (Lake Rosslängen in Calmar Län)! Mouth of Jenissey! Demerara River! 



19. C. aeutiuscula Cl. N. Sp. — V. slightly asymmetrical, lanceolate. gradnally tapering 

 from the middle to the acnte 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 aronnd the central nodule. Strife 9 to 10 

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

 pnnctate; puncta 17 to 20 in 0, 01 mm. — Pl. IV f. 26. 



Fresh water: Crane Pond! Waltham, Mass.! 



This species is nearly akin to C. acuta, bnt has broader area and raore coarsely pnnctate striic. 



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

 slightly convex ventral mai'gin and obtnse, not rostrate ends. L. 0, 07 to O, os; B. O.ois to O.02 

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

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

 to 18 (ends) in 0, 01 mm., radiate throughont, coarsely pnnctate; pnncta about 18 in O.oi mm. — 

 V. H. in Hanck and Richter Phycoth. univ. N:o 147. Notari,sia 1888 p. &22. Icon. n. Pl. IV f. 24. 



Fresh water: Triest! 



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

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

 in the middle. C. Lindsayana GtREv. (Träns. Bot. Soc. Edinb. Vol. VIII p. 234 Pl. III f. 5 to 8) 

 has the same size and ontline as C. Hauclcii, but, according to (treville, somewhat coarser stri;e. 

 The description and figures given by GtREVILLE are not snfHcient for identihcation. 



21. C. amphicephala Naeheli (1849). — V. slightly asymmetrical, with arcuate dorsal and 

 almost straight ventral margin. Ends rostrate to rostrate-capitate. L. 0,025 to O.04 ; B. (•.oo;» to 

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

 Strite 12 or 14 (dorsal) to l(i (ventral) in 0, 01 mm., more distant in the middle than elsewhere. 

 slightly radiate. — Naecj. in Ktitz. Sp. Alg. p. 890. A. S. Atl. IX f. 62, 64 to \3ii\ LXXI f. 52. 

 V. H. Syn. p. 61 Pl. II f. 6. C. iiaviculiformi.s Heib. Consp. Crit. p. 108 Pl. I f. 2. 



Fresh water: Spitsbergen! Iceland! Sweden (Areskutan, Upsala. Rillingeii. (tuU' of Butlmia)! 

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

 New Zealand! Brazil! 



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

 L. 0,04; B. 0,007 mm. Strire in the middle 16, at the ends 18 in 0, 01 mra. 



Fresh water: Norway, Dovre! 



