74 p. T. OLKVE, SYNOPSIS OF THE NAVIOULOID DIATOMS. 



I. Gracillimee. 



Artificial licy. 



Ends rounded . . . ' - g. 



capitate or rostrate 4. 



^ ( Stria; not interrui)ted P. suhlinearis Grun 



" ( — interrupted ;i. 



para 



middle sliglitlv radiate P. molaris Grun. 



{ 



'i 



g ( Striffi almost parallel P. leptosnnm Grun. ') 



I -- in the middle <sliglitly radiate P. molaris Grun 



^ J Ends capitate P. nndulatn Grkg 



— rostrate P. gracillhna Greg. 



1. P. gracilliniii (tREo. (1856) — V. linpar, tiiiindulate, with rostrate to suboapitate ends. 

 L. 0,026 to 0,03; B. U,()oo mm. Areas indi.stinet. Strite, 18 to 22 in 0,oi mm. almost parallel. — 

 M. J. IV PI. r f. 31. Nar. f/r. V. H. S. PI. VI f. 24. N. mfsoii/Ia Schum. Tatra D. PI. IV f. 51? 



Fresh water: Scotland ((rreg.), Greenland! 



2. P, uiidiilata Greg. (1854). — V. linear, witli more or less distinctly triundulate margins 

 and broad, capitate ends. L. 0,03 to O,os:r, B. (),()(mi mm. Axial area indistinct; central area or- 

 bicular or a transverse fascia. Stritc 22 in (»,()i mm., almost parallel, convergent at the ends. — 

 M. J. II, PI. IV f. 10. — Cl. D. of Finland p. 30 PL TI f. 8. 



Fresh water: Sweden (Pautriisk in Stensele Lappmark)! Finland, Savitaipale Dept! Scot- 

 land (Greg.). 



Var. siibundidata Grun. — V. with less distinctly undulated margins. Striae 18 to 21 in 

 0,01 mm., not interrupted. — V. H. Types N:o 140. 



Fresh water: Scotland (V. H. f.). 



As far one may judge from the figures Nar. nicsofijlct Schum. and P. (irnciUima are the 

 same species, and the only difference between them and F. undnlata consists in the broad, capitate 

 ends of the latter. 



3. P. subliiiearis Grtin. (1880). — V. narrow, linear, slightly gibbous in the middle, with 

 rounded ends. L. 0,02 to 0,03; B. 0,004 mm. Areas indistinct. Strite 21 to 24 in 0,oi mm. 

 slightly radiate in the middle, convergent at the ends. — Nav. suhj. (jrun. V. H. Syn. p. 7»j 

 PI. VI f. 25, 26. P. tenuis Greg. M. J. 1854 p. 97 PL IV f. 9? 



Fresh Avater: Greenland! 



4. P. leptosoma Grun. (1880). — V. narrow, linear, with rounded ends. L. 0,035 to 0,o4 ; 

 B. Ojoof) mm. Median line with approximate central pores. Axial area very narrow; central area 

 a broad, transverse fascia. Striif 14 or 17 (middle) to K! or 20 in 0,oi mm. (at the ends) almost 

 parallel. — Nav. leptos. Grun. in V. H. Syn. XII f. 29. 



Fresh water: Sweden (Rimforsa in Westergotland)! Finland! 



5. P. molaris Grun. (1863). — V. linear, slender, with rounded or subcuneate ends. L. 

 0,033 to 0,0.') ; B. 0,005 to 0,008 mm. Axial areal narrow or indistinct; central area a broad, trans- 

 verse fascia, reaching to the margin. Striee 15 to 17 in 0,oi mm., slightly radiate in the middle, 

 convergent at the ends. — Na.v. molaris Grun. Verb. 1863 p. 149 PL IV f. 2Q. V. H. Syn. 

 PL VI f. 19. Nav. macra A. ^. Atl. XLIV f. 54. Nav. mesoleia Cl. N. R. D. p. 10 PL II f. 'lij. 



Fresh water: Norway (Dovre)! Scotland! Sweden! Denmark (Ringkcibing Atl.), Finland! 

 (Termany (Grun.), Brazil! Uemerara River! Cape Horn! Bengal! 



P. molaris is nearly akin to P. leptosoma, whicli differs by nothing except the less radiate 

 median and the closer terminal striae. 



') Conf. P. isostauron Grun. 



