KONGL. 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. Among other Naviculoids no kindred forms are known, except in the genus Cocconeis of 

 which some species seems to be degenerate forms of Mastogloia. 



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

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

 as M. Smithii, M. elliptua, 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 '). 



1. 

 8 



3. 



4. 

 5. 



6. 



7. 



8. 



9. 

 10. 

 11. 

 12. 

 13. 

 14. 

 15. 

 16. 

 17. 

 18. 

 19. 



Artificial Icey. 



I Strnctnre donble, of costsfi and pnncta 



1 — simple, of pnncta only . 



I Valve linear with cuneate ends 



I — elliptic-lanceolate 



I Puncta arranged in decussating rows .... 



\ — not — 



/ Ends subacute, more or less rostrate .... 



) — broad, rounded 



{Striae about 22 in 0,oi mm. . . 

 - - 13 - - 



{Loculi 9 In 0,oi mm 

 — 8 to 4 - 



I Valve with longitudinal furrows . . . 



I — without — — 



/ Ends rostrate 



I — subacute, M. Grovei Cl. {M. Bahamensis Cl., 



/ Loculi lunate 



I — quadrate or rectangular 



{Median loculi larger than the others . . 

 ■ — not — — — 



J Terminal loculi larger . . 



1 — — not — . . ... 



j Rim of loculi reaching to the ends . . 



/ Loculi Innate .... ... 



\ — quadrate .... 



I Loculus single unilateral 



I Loculi few 



/ Central area a transverse fascia .... 



{Median line between two rows of puncta 

 — — not enclosed between rows of 

 {Puncta along the median line rounded 

 — • — — — — elongated . 

 / Transverse rows of puncta ending near the margin in double rows 



{Rows of puncta 5 to 6 in 0,oi mm 



M. 



puncta 



. . . 2. 



3. 



. M. Grevillei W. Sm. 

 M. Castracanei Pant. 

 4. 

 22. 

 5. 

 13. 

 6. 

 8. 

 decussata Gbun. 

 M. delicatula Cl. 

 ... 7. 

 M. sulcata Cl. 

 . M. Kjellmanii Cl. 



9. 



M. Jelineekiana Geun.). 

 . . . M. Rhombus Pet. 



10. 



M. angulata Lewis. 



11. 



. . M. rostellata Gkun. 



12. 



. . M. asperula Gkun. 

 M. Szontaghii Pant. 



14. 



16. 



. M. hinotata Grun. 



15. 



. . M. Crucicula Geun. 

 . . M. fimbriata Btw. 

 . . .... 17, 



18. 



. . . M. Wrighfii O'M. 

 . M. Barbadensis Geev. 

 of small puncta . 19. 

 — — . 20. 



. M- Clevei Geun. 

 . 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 Mastoglois are figured. Before printing this monograph I have completed the text with 

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

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

 unable to identify with known forms. 



