170 r. T. CLEVE, SYNOPSIS OF THE NAVICULOII) DIATOMS. 



terminal nodules at some distance from the ends. Axial area narrow, central area small, orbicular. 

 Striic 14 to 15 in 0,oi mm. slightly radiate in the middle, where they are more distant, parallel 



at the ends. — Grun. in A. S. Atl. X f. 41. (Jl. M. D. N:o 2(58. 



Fresh water (alpine regions): (Ireenland! Iceland! Norway (Dovre, Romsdalen)! Sweden 

 (Paiitriisk, Wilhelmina socken)! 



C. norvegica is nearly akin to G. (jracilts and ditFers principally by its more linear form 

 and broad, rounded ends. 



44. C iucerta Grun. (1878). — V. linear, slightly asymmetrical, with broad, obtuse ends, 

 slightly arcuate dorsal margin and almost straight ventral. L. 0,o4 to 0,o7;B. 0,oo9 mm. Median 

 li)ie almost central. Axial area narrow, not dilated in the middle. Stritc 14 to 1(> in 0,01 mm., 

 equidistant in tlie middle, where they are parallel, and slightly radiate at the ends. — C Pisciculus 

 var. inccrta Grun. CI. M. D. N:() 96. Cl. I). tV. Grihil. och Argent, p. 13 PI. XVI f. 12. C. siih- 

 a;qu(il'is var. 'inccrta Grun. in V. H. T. N:o 30. 



Fresh water, northern or alpine regions: Norway (Dovre, Hammerfest)! Sweden (Lapland)! 

 Finland (Rns.sian Lapland)! Scotland (V. H. T.). 



Var. naricnJacca Grun. (1879). — With somewhat wider axial area and finer stride, about 

 18 in 0,01 mm. — C. (Pisciculus var.) vnrindncca Grun. in Cl. M. I). N:o 272. Cl. D. fr. Grfinl. 

 och Argentina p. 13 PI. XVI f. 11. 



Fresh water: Greenland! Norway (Dovre)! Sweden (Lapland to Jiimtland)! Finland (Riassian 

 La-jdand)! 



4'). 0. sequalis W. Sm. (18r)()). — V. linear-lanceolate, with arcuate dorsal, straight or 

 slightly convex ventral margin, and broad, obtuse, or almost truncate ends. L. <),((.3 to 0,045; B. 0,oog 

 to 0,011 mm. Median line straight, near to the ventral margin, broad (oblique). Axial area 

 narrow, not, or slightly, dilated in the middle. Strios 11 or 14 (middle) to 14 or 16 (ends) in 0,oi 

 mm., slightly radiate, obscurely punctate; pimcta about 16 in O.oi mm. — W. Sm. B. D. II p. 84. 

 OijTnh. ohinsa Greg. M. J. IV PI. I f. 19 (1856). V. H. Syn. p. (U PI. Ill f. 1 a. A. S. Atl. IX 

 f. 41 to 45; LXXI f. 72? Cymh. suhcequalis Grun. V. H. Syn. PI. Ill f. 2, 4 Snppl. A f. 1 (1880). 



Fresh water: Greenland! Iceland! Scotland and England! Sweden (Lapland to Skane, Goth- 

 land)! Norway (Dovre, Stavanger, foss.)! Belgium (V. H.), Saxony! Switzerland! Michigan! 



Var. florcnt'ina Grun. (1880). — V. less asymmetrical, almost lanceolate. Stria? finer, 15 in 

 0,01 mm. — Cijiuh. snhfcqualis var. florciilind Grun. in V. H. Syn. PI. Ill f. 3. 



Fresh water: S:ta Flora, foss. (Grun.). 



Var. diminida Grun. — L. 0,oi.'i; B. 0,004 mm. Striae 12 to 15 in 0,oi mm. — Cymh. obtusci 

 var. diminuta Grun. in A^. H. T. N:o 129. 



Fresh water: England (V. H. T.). 



C. ceqnalis W. Sm. is usually believed to denote the same species as C. atujiisfafd, but as 

 the ends are described as obtuse and the striffi are coarse, 12 iii 0,oi mm., it is evident that 

 this is a mistake, and that Smith meant the form described above as C. (rqiudis. Gregory's figure 

 of (h/mh. ohtusa is small and not very characteristic, but agrees pretty well with this S2)ecies. 

 Between Cijhih. sub(cqii(dis Grun. and Cymh. ohtusa Greg, as represented in Van Heurck's Synopsis 

 I am unable to discover any specific distinction. As limited here Cymh. (cqualis is a common 

 form, distinguished by its linear form and almost truncate ends. The median stria; are more dis- 

 tant tlian the otliers and radiate. 



46. (J. sinuata (tREO. (1856). — V. linear, slightly asymmetrical, fre(|nently gibl)ous in the 

 middle on the ventral side, with l)road, obtuse ends. Ij. 0,oi2 to 0,o2g; B. 0,oo4 to 0,oor) mm. 

 Axial area narrow; central area large, on the ventral side reaching to the margin. StritC 9 to 11 

 0,01 mm., almost parallel. — Greg. M. J. IV PI. I f. 17. C. ahnormis Grun. in V. H. Syn. PI. Ill 

 f. S (18S0). Gomj)/ioiir)na (isyiuiiKiricnm, (tUTW. ]). 2X IM. 1 f 24? 



