K0N6L. SV. VET. AKADEMIENS HANDLINGAR. BAND. 27. N:0 3. 143 



however, occur between these types, and I see no reason for splitting up the genus on this 

 account. Araong other Naviculoids no kindred forms are known, except in the genus Cocconeis of 

 whicli some species seems to be degenerate forms of Mastogloia. 



The species of Mastogloia live in gelatinous mammillate masses, the formation of whicli 

 seems to have some connection with the loculi. A few only inhabit perfectly fresh water. Some 

 as M. Smithii, M. elliptica, M. exigua, M. lanceolata are abundant in brackish water. A. small 

 number of species are found in the Arctic seas, but the majority occur in tropical seas. 



I have placed the small Diadesmis gallica W. Sm. in Mastogloia, on the supposition that 

 the marginal puncta of this species are loculi, which is not easy to decide as the form is so ex- 

 cedingly small '). 



Artificial hey. 



I 



I 



^ ( Structnre donble, of costsfi and puncta 2. 



\ — simple, of puncta only • 3. 



,, I Valve linear with cuneate ends M. Grevillei AV. Sm. 



\ — elliptic-lanceolate M. Cnstracanei Pant. 



g I Puncta arranged in decussating rows 4. 



■ t — not — 22. 



. I Ends subacute, more or less rostrate 5. 



I — broad, rounded l.S. 



P j Stri» about 22 in 0,oi mm 6. 



■'■ \ — — 13 - — 8. 



f Loculi 9 in 0,oi mm M. decussata Geun. 



6. < — 6 — — M. delicatula Cl. 



I - 3 to 4 - ■ 7. 



- ) Valve with lonsitndinal fnrrows M. sulcata Cl. 



I — without — — M. Kjellmanii Cl. 



„ J Ends rostrate 9. 



\ — subacute , M. Grnvei Cl. (M. Baliamenaiss Cl., M. Jelineckiana Geun.). 



Loculi lunate M. Rlwmbus Pet. 



quadrate or rectangular 10. 



j Media 



-., . Terminal loculi larger M. rostellata Geun. 



^^- ^ not - 12. 



.{ 



,^ , Median loculi larger than the others M. a'ngiilata Lewis 



not — — — 11. 



i 



..„ I Rim of loculi reaching to the ends M. asperula Geun. 



\ — — not — — — M. Sznnfagini Pant. 



..„ I Loculi lunate 14. 



I — quadrate 16. 



J Locnlus single unilateral M. binotata Geun. 



I Loculi few 15. 



^ ^ j Central area a transverse fascia M. Crucicida Geun. 



' ■ I — — not — — M. fimbriata Btw. 



..„ j Median line between two rows of puncta 17. 



' \ — — not enclosed between rows of puncta 18. 



..„ j Puncta along the median line rounded M. Wrightii 0'M. 



■ \ — — — — — elongated • M. Barhadensis Geev. 



.„ J Transverse rows of puncta ending near the margin in double rows of small puncta . 19. 

 ^*^- \ - _ _ not - - - - - - _ . 20. 



„ ( Rows of puncta 5 to 6 in 0,oi mm M. Clevei Geun. 



'■\ — — — 8 — — M. splendida Geeg. 



') The following monograph was already completed, when the plates 185 to 188 of A. Schmidt's Atlas were issued, 

 in which a considerable number of Mastogloia^ are figured. Before printing this monograph I have completed the text with 

 quotations, but I conld not change the artificial key, as most of the new species are not represented in sufficient detail for 

 being admitled into the system. The reader will "find at the end of this monograph a list of the new species, which I am 

 nnable to identify with known forms. 



I 



