190 p. T. CLEVE, SYNOrSKS OF THK NAVICULOH) DIATOMS. ' 



0. A. trinodis Arnott (1861). — Linear, gil)l)ou.s in the initliUe and at tlie broad ends. 

 L. 0,0 15 to 0,02; B. 0,00') mm. Upper- V. with narrow axial area dilated in the middle to an 

 almost orbicnlar, small central area. Stria; about 30 in 0,oi mm. parallel. Lower V. without 

 distinct axial area and with small central area. Striie about oO in 0,oi mm. parallel. — Achnan- 

 thulium frinodc Pritch. Inf. p. 872 PI. VllI f. 9. Nar. trinodis Grun. Verb. 1860 p. 551 PI. IV 

 f. 8. Bhoiconeis iriti. Grun. Verb. 1863 p. 147. Arln>. trln. V. H. Syn. PL XXVII f. 50 to 52. 



Fresh water: England, Tyrol (Grun.). 



10. A. delicsitula Kutz. (1844). — Elliptic-lanceolate, frequently with subrostrate ends. 

 L. 0,01 to 0,02; B. 0,()o,j to 0,011 mm. Upper \. with narrow, linear axial area. Striae 14 to 15 

 in 0,01 mm. almost parallel. Lower V. with indistinct axial area and very small, orbicular central 

 area. Striye 17 to 19 in 0,oi mm. the median shorter. — Achnantliidhini dclicatitlum Kutz. Bac. 

 p. 75 PI. Ill f. 21. Adinanthes delic. Grun. A. L). p. 22, 1880. V. H. Syn. p. 130 PI. XXVII f. 3, 4. 



Brackish water: Greenlaiul! Arctic America! North Sea! English Channel! Balearic Islands! 

 San Francisco! 



11. A. Haiidiisma Grun. (1880). — Elliptical to elliptic-lanceolate. L. 0,012 to 0,0:51; 

 B. 0,ooG to 0,008 mm. Upper V. with linear, narrow axial area. Striae. 10 to 12 in 0,oi mm., 

 parallel, lower V. without axial area and with small central area. Strife 10 to 13 in 0,oi mm. 

 radiate. — A. D. p. 21. Achn. Bauclm Grun. V. H. Syn. PI. XXVII f. 14, 15. 



Hot springs and brackish water: Triest (Grun.), Canada! New Zealand! Tasmania! Cape Horn! 



12. A. afiillis Grun. (1880). — Linear-lanceolate, obtuse. L. 0,oir) to 0,023; B. 0,oo3 to 

 0,0 3.=) mm. Upper V. with narrow, linear axial area. Strice parallel 27 to 30 in 0, 01 mm. Lower 

 V. with narrow axial area. Central area a transverse fascia, reaching to the margin. StritB about 

 30 in 0,01 mm. radiate throughout. — A. D. p. 20. V. H. Syn. p. IbM) PI. XXVII f. 39, 40. 



Fresh water: Belgium (V. H.), Tasmania! North America, White Mountains! 

 Var. jmnulinensis Grun. (1880). — L. 0,037; B. 0,005 mm. Strife of the lower V. 16 in 0,oi 

 mm. — A. Jumgarica var.? jamal. Grun. A. D. p. 20. 

 Marine (?): Sea of Kara (Grun.). 



13. A. exigua Grun. (1880). — Broadly elliptic-lanceolate, with rostrate, obtuse ends. 

 L. 0,0 13 to 0,017; B. 0,005 to 0,006 mm. Upper V. with narrow, linear axial area. Striae about 

 22 in 0,01 mm. parallel. Lower V. with very narrow axial area. Central area a transverse 

 fascia, reaching to the margin. Strife about 25 in 0,oi mm. slightly radiate throughout. — Sfauro- 

 neis exilis Kutz. Bac. p. 105 PL XXX f. 21. Schum. Preuss. L)'. II Nachtr. PL II f. 59. Ach. 

 exi(/na Grun. A. D. p. 21. V. H. Syn. PL XXVII f. 29, 30. 



Fresh water, hot springs: Sweden (Hernosand, interglacial deposit)! Germany (Berlin)! 

 Brazil! Ecuador! Surinam! Java! New Zealand! Hawaii! 



14. A. hungarica Grun. (1863). — Narrow elliptical or linear-lanceolate with subcuneate 

 ends. L. 0,02 to 0,03; B. 0,oo6 to 0,oo7 mm. Upper V. with narrow axial area, in the middle 

 dilated to a narrow, short, transverse central area. Striae about 21 in 0,oi mm., parallel. Lower 

 V. with narrow axial area. Central area a broad fascia. Striae about 21 in 0,oi mm., slightly 

 radiate. — Achnanthidium hurtgaricum Grun. Verb. 1863 p. 146 PL IV f. 8. Achnanthcs hung. 

 A. D. p. 20. V. H. Syn. p. 130 PL XXVII f. 1, 2. Achnanthidium ncglcdmn Schum. Preuss. 

 D. II Nachtr. p. 54 PL I f. 17? 



Fresh water: Sweden (Grun.), Belgium (V. H.), Hungary (Grun.), Illinois! Brazil! Ecuador! 

 Australian Alps (Rieva Lagoon)! 



To this group may belong Achnanthes Gregori/ana Grev. (M. J. VII p. 84 PL VI f. 13, 14) 

 if this form, of which the zonal view is figured, be really an Achnanthcs, but it appears more 

 probable that it may represent an arcuate Gyrosigma perhaps G. arcticum. 



