130 P. T. CLEVE, SYNOPSIS OF THE NAVICULOID OIATöMS. 



Var. Pec/uana Grun. (1879). - V. lanceolate, slightly triundulate with subacute ends. L. 

 0,04; B. 0,0 1 mm. Stritt in the middle 15 at the ends 20 in 0,01 mm. — Gru.v. Cl. M. D. X:o 188. 



Brackisli water: Bengal! 



Var. Legumen Cl. — V. linear, triundulate, with cuneate, acute ends. L. 0,o.35; B. 0,uo9 

 mm. StriiB 21 in 0, 01 mm. 



Fresh water: Surinam! 



Forma imdnlata Hilse (1860). — V. with three to Ibur undulations on the margins. — 

 Stauroneis undulaia Hilse Beitr. p. 83. Nav. viutica v. muhdata GrRUN. A. D. p. 41. V. H. Sjai. 

 p. 95 Pl. 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 pnnctum in tlie area. 



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

 0,022; B. 0,0054 to 0,006 8 mm. Axial area narrow. Central area large transversely dilated, without 

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

 — Grun. Verh. 1860 p. 538 Pl. IV f. 12. A. D. p. 41. JSTav. Kot^clnjana V. H. Syn. Pl. X f. 22. 



Fresh water, hot springs: Buda-Pest! 



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

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

 out an isolated punctum. Striaj 16 in 0,oi mm. — Staitron. Heufleriana Grun. Verh. 1863 p. 155 

 Pl. IV f. 10. St. Hcufleri. 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 dilFerence 

 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. Striie 18 to 19 in 0, 01 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. quinqnenodis Grdn. 

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

 f. 5. N. unclosa Donk. B. D. p. 37 Pl. VI f. 1 (1871). 



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

 Australia ! 



13. N. obliqua Greg. (1856). — V. broad, elliptic-lanceolate. L. 0,04; B. 0,oi6 mm. Median 

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

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

 wider. Stria; 21 in 0,oi mm., in the middle a little raore distant, almost parallel. distinctly 

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

 Stauroneis ohliqua Greu. M. J. IV p. 11 Pl. I f. 35. N. ohl. Icon. n. Pl. V f. 26. 



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

 mud from Vettern! 



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

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

 tion of Gregory. On original specimens from Loch Leven in Debv's collection I could not distincth- 

 see the sigmoid flexure of the median line. Neither could I tind 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 witli Sianroncis ohliqua Greg. 



