4 P. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



5. N. microcepliala Grun. (1880). — V. lanceolate, obtuse. L. 0,oi4; B. 0,oo3 mm. Areas 

 indistinct. Strite nearly parallel, about 30 in 0,oi mm. — V. H. Syn. Pl. XIV f. 29. Ächnan- 

 thidium microc. W. Sm. B. D. II p. 31 Suppl. Pl. LXI f. 380 (1856)? 



Fresh water. 



6. N. Atoinus Naegeli (1849). — V. elliptical, with rounded ends, sligbtly silioious. 

 L. 0,004 to 0,008; B. 0, 002.') to 0, 004 mm. Areas indistinct. Strise abont 30 in 0, 01 mm. strongly 

 radiate thronghont. — Synedra At. Naegeli in Kiitz Sp. Alg. p. 40 (according to Grnnow). N. Åt. 

 Grun. Verh. 1860 p. 552 Pl. IV f. 6. V. H. Syn. p. 107 Pl. XIV f. 24, 25. 



Fresh water (Moist earth etc.): Belgium (V. H.). 



7. N. (Diadesmis) lucidula Grun. (1880). — V. elliptical, with broad, rounded ends. 

 L. 0,015 to 0,019; B. 0,0085 to 0,01 mm. Areas indistinct. Strise 17 in 0, 01 mm. slightly radiate 

 thronghont, distinctly pnnctate, ptincta forming longitndinal rows, about 17 in 0, 01 mm. — V. H. 

 Syn. Pl. XIV f. 40. 



Fresh water. 



8. N. minuscula Grun. (1880). — V. elliptic-lanceolate, with obtuse ends. L. 0,012; B. 0,oo5 

 mm. Areas indistinct. Strise about 30 in 0,oi mm. almost parallel. — V. H. Syn. Pl. XIV f. 3. 



Fresh water. 



9. N. bahusiensis Grun. (1880). — V. broadly lanceolate, with subrostrate ends. L. 0,oi3 

 to 0,02; B. 0,006 mm. Areas indistinct. Stria; 25 in 0,oi mm. almost parallel. — N. minusc. v. 

 baJi. V. H. Syn. Pl. XIV f. 2. 



Marine: West coast of Sweden! 



Var. istriana Grun. (1880). — V. more lanceolate. Strise 22 in 0,oi mm. — V. H. Syn. 

 Pl. XIV f. 4. 



Marine: Adriatic (Grun.). 



Var. arctica Grun. (1884). — V. broadly lanceolate. L. 0,02 to 0,02i; B. 0,0095 mm. Strise 

 21 in 0,01 mm. radiate throughout. — Fr. Jos. Land, U. p. 104 (52) Pl. I f. 43. 



Marine: Franz Josefs Land (Grun.). 



Naviculse Decussatae Grun. (18G0 p. p.). 



Valve elongated, elliptical, or lanceolate, symmetrical, not sigmoid. Structure: puncta ar- 

 ranged in obliquely decussating rows. 



This small group compi-ises three isolated forms, which seem not to be allied to each other. 

 N. Placentula is a fresh-water species, perhaps akin to the Fimctatce, although it has no nearly allied 

 species in that group. JV. decussata is too imperfectly described to decide what are its affinities. 

 The termination of the median line at a distance from the ends suggests an affinity to the section 

 Microstigmaticte (division Libelliis). N. Quincimx is an entirely isolated form, the structure of 

 which recalls that of some Mastogloise, but from the straight median line it may be inferred that 

 it really is a Navicula. 



1. N. Placenta Eiib. (1854). — V. elliptical, with rostrate-capitate ends. L. 0,037 to 0,039; 

 B. 0,015 to 0,0 17 mm. Axial area indistinct. Central area small, orbicular. Transverse strise 22 

 (middle) to 27 (ends) in 0, 01 mm. slightly radiate. Obliqne stripe curved, crossing each other at 

 an angle of about 80°. — M. G. XXXIII, 12 f. 23. Lewis Proc. acad. nat. sci. Philad. p. 7 

 Pl. II f. 7 (1865). Gkun. a. D. p. 47 Pl. III f. 60. iV. apiculata Greg. M. J. IV p. 4 Pl. I f. 13 

 (1856). N. liostdlum W. Sm. B. I). II p. 93 (1856). Grun. Verh. 1860 p. 550 Pl. IV f. 10. 

 DoNK. B. I), p. 40 Pl. VI f. 7. 



