130 p. t. CLEVE, SYNOPSIS Off THE NAVlCULOlU DIATOMS. 



Var. Peguana Grun. (1879). — V. lanceolate, slightly triundulate with subacute ends. L. 

 0,04; B. 0,01 mm. Striae in the middle 15 at the ends 20 in 0,oi mm. — Grun. CI. M. D. N:o 188. 



Brackish water: Biengal! 



Var. Legumen Cl. — V. linear, triundulate, with cuneate, acute ends. L. 0,035; B. 0,oo9 

 mm. Striae 21 in 0,o) mm. 



Fresh water: Surinam! 



Forma undulata Hilse (1860). — V. with three to four undulations on the margins. — 

 Stauroneis undulata Hilse Beitr. p. 83. Nav. mutica v. undulata Grun. A. D. p. 41. V. H. Syn. 

 p. 95 PI. X f. 20 c. 



Brackish water: South Africa! Ecuador! 



N. mutica is a very variable species, having the appearance of a Stauroneis, under a low 

 power. All varieties have the unilateral isolated punctum in the area. 



10. N. Kotschyii Gkun. (1860). — V lanceolate, rostrate, with obtuse ends. L. 0,oi36 to 

 0,022; B. 0,0054 to 0,0068 mm. Axial area narrow. Central area large transversely dilated, without 

 an isolated punctum. Striae 19 to 23 in 0,oi mm., closer near the ends, radiate, distinctly punctate. 

 — Grun. Verb. 1860 p. 538 PL IV f. 12. A. D. p. 41. Nav. Kotschyana V. H. Syn. PL X f. 22. 



Fresh water, hot springs: Buda-Pest! 



11. N. Heufleriana Grun. — V. inflated, with large capitate and flattened ends. L. 0,0244 

 to 0,032; B. 0,008 to 0,009 mm. Axial area indistinct. Central area large, almost quadrate, with- 

 out an isolated punctum. Striae 16 in 0,oi mm. — Stauron. Heufleriana Grun. Verb. 1863 p. 155 

 PL IV f. 10. St. Heufleri. V. H. Syn. PL IV f. 1 a. 



Fresh water: Tyrol (Grun.). 



This form is very nearly connected with N. mutica var. ventricosa, almost only difference 

 being absence of an isolated punctum in the central area. 



12. N. nivalis Ehb. (1854). — V. with triundulate margins and rostrate-truncate ends. 

 L. 0,0122 to 0,018; B. 0,00 54 mm. Axial area indistinct, central area large, rounded-quadrate, 

 without an isolated punctum. Striae 18 to 19 in 0,oi mm. radiate to the ends and composed of 

 distinct puncta, 18 to 24 in 0,oi mm. — Ehb. M. G. XXXIII B. a f. 5. N. quinquenodis Grun. 

 Verb. 1860 p. 522 PL III f. 33. Verb. 1863 p. 149 PL IV f. 9. Cl. D. of Finland p. 33 PL II 

 f. 5. N. undosa Donk. B. D. p. 37 PL VI f. 1 (1871). 



Fresh water: Sweden (Upsala)! Finland! Belgium (V. H.), Brtinn (Grun.), Blue Mountains, 

 Australia! 



13. N. obliqua Greg. (1856). — V. broad, elliptic-lanceolate. L. 0,04;B. 0,oi6mm. Median 

 line slightly sigmoid, with the ends in contrary directions. Axial area very narrow or indistinct; 

 central area a broad transverse fascia, almost reaching to the margin, where it becomes somewhat 

 wider. Striae 21 in 0,oi mm., in the middle a little more distant, almost parallel, distinctly 

 punctate; puncta about 21 in 0,oi mm., arranged in somewhat undulating longitudinal -rows. -- 

 Stauroneis obliqua Greg. M. J. IV p. 11 PL I f. 35. N. obi. Icon. n. PL V f. 26. 



Fresh water: Scotland (Loch Leven) Greg., Engl. "Windermere, Grove Coll.! Sweden, bottom- 

 mud from Vettern! 



Gregory's figure shews no structure and a decided sigmoid bent of the median line. The 

 above description is from a specimen in Groves collection, which perfectly agrees with the descrip- 

 tion of Gregory. On original specimens from Loch Leven in Deby's collection I could not distinctly 

 see the sigmoid^ flexure of the median line. Neither could I find the median line sigmoid on 

 specimens from Abo (Diat. of Finl. p. 34 PL III f. 1), Oregon and the mouth of the Jenissey. Having 

 had no opportunity of reexamining these specimens I am unable to state whether I am guilty of 

 a mistake on this point, or these forms represent a variety with straight median line. In all cases 

 the above description refers to a specimen, doubtless identical with Stauroneis obliqua Greg. 



