4 1'. T. CLEVE, SYNOPSIS OF THE XAVICU[-OID DIATOMS. 



5. N. microcephala Grun. (1880). — V. lanceolate, obtuse. L. 0,014; B. 0,oo3 mm. Areas 

 indistinct. Striffi nearly parallel, about 30 in 0,oi mm. — V. H. Syn. PI. XIV f. 29. Achnan- 

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



Fresh water. 



6. N. Atoinus Naegeli (1849). — V. elliptical, with rounded ends, slightly silicious. 

 L. 0,004 to 0,008; B. 0, 002.1 to 0,oo4 mm. Areas indistinct. Strife, about 30 in 0,oi mm. strongly 

 radiate throughout. — Syncdra At. Naegeli in Kiitz Sp. Alg. p. 40 (according to Grrunow). N. At. 

 Grun. Verb. 18G0 p. 552 PI. IV f. G. V. H. Syn. p. 107 PI. XIV f. 24, 25. 



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



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

 L. 0,0 15 to 0,019; B. 0,0085 to 0,01 mm. Areas indistinct. StricB 17 in 0,oi mm. slightly radiate 

 throughout, distinctly punctate, puncta forming longitudinal rows, about 17 in 0,oi mm. — V. H. 

 Syn. PI. 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. Strife aboixt 30 in 0,oi mm. almost parallel. — V. H. Syn. PI. 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. Strict 25 in 0,oi mm. almost parallel. — N. minusc. v. 

 hah. V. H. Syn. PI. XIV f. 2. 



Marine: West coast of Sweden! 



Var. istriana Grun. (1880). — V. more lanceolate. Strife 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 0,021; B. 0,ooy5 mm. Strife 

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



Marine: Franz Josefs Land (Grun.). 



Naviculae Decussatse Grun. (18^)0 p. p.). 



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

 ranged in olJiquely decussating rows. 



This small group comprises three isolated forms, which seem not to l)e allied to each other. 

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

 species in that group. N. 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 

 Microstigmaticce (division Lihvllns). N. Quincunx is an entirely isolated form, the structure of 

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

 it really is a Navicula. 



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

 B. 0,0 15 to 0,0 17 mm. Axial area indistinct. Central area small, orbicular. Transverse strife 22 

 (middle) to 27 (ends) in 0,oi mm. slightly radiate. Oblique strife curved, crossing each other at 

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

 PI. II f. 7 (18(!5). Grun. A. D. p. 47 PI. Ill f. 60. N. apiculata (4re(J. M. J. IV p. 4 PI. I f. 13 

 (1856). N. Rostellum W. Sm. B. D. II p. 93 (185()). Grun. Verb. 1860 p. 550 PI. IV f. 10. 

 Donk. B. D. p. 40 PI. VI f. 7. 



