KONGL. vSV. VET. AKADKMIENS Ily\N I)l>IN(;Ali. BAND 



27. n:() 3. 17;^ 



This small and characteristic form is figured by Schumann with median line and central 

 nodule, of which I have never seen a trace. 



10. 0. aiistralis Petit (1877). — Outline elliptical. L. 0,0204; B. 0,()242 mm. Upper V. 

 unknown. Lowei' V. with sigmoid median line and the terminal nodules in contrary directions, at 

 some distance from the margin. Margin witli rudimentary loculi. Striae fine. — D. de Campbell 

 p. 11 PI. IV f. 2. 



Marine: New Zealand (Petit). 



This species has the appearance of being very distinct, but it is, unfortunately, incompletely 

 described and figured. 



11. C. Van Henrckii Cl. N. Sp. — Elliptical. L. 0,0:55 to 0,04; B. 0,oi5 to 0,024 mm. 

 Upper V. with a straight axial silicious rib, sending off' on both sides strong costai, 4 to 5 in 0,oi 

 mm., coniiected by longitudinal silicious ribs, 2 to 4 on each side, thus forming a reticulum of 

 large, quadrate alveoli. Lower V. with straight median line, not reaching to the margin, and a 

 narrow, but distinct marginal area. Axial area indistinct. Central area small, rounded. Striaj 

 18 in 0,01 mm. slightly radiate, punctate. — PI. II f. 32, 33, 34. 



Marine : Madagascar ! 



The very peculiar upper valve of this species makes it doubtful whether it really belongs 

 to this group, but on the other hand the lower valve resembles that of C. Scutellnm. This 

 species may be the same as Cocc. siirirelloides Grun. (Novara p. 98 PI. I A f. 27, 28; 1867) but 

 the descriptions and figure are insufficient for identification. 



Eucocconeis Cl. N. G. 



Valves elliptical, rarely rostrate, without a marginal rim, ecostate, usually not very dis- 

 similar. Striation of both valves unusually delicate. Upper valve with a narrow axial area. 

 Lower valve with straight or sigmoid median line. 



This group comprises most species of the old genus Cocconeis. Its affinities are difficult to 

 decide. In outline of the valves it resembles Cocconeis Cl., from which it is distinguished by the 

 absence of the loculiferous rim '). In the usually fine striation of both, not very dissimilar, 

 valves, it approaches Microncis. C. flexclla and C ininuta are isolated forms recalling Navicula 

 cleprcssci and N. Rotaeanu. 



Artificial hey. 



I j Ujjpei' valve witli lateral areas or furrows '.'. 



' \ — — without • 2. 



. j Ui)per valve with an unilateral horseshoe-shaped marking 3. 



) — — without 4. 



M 



Striation tine, median line straight A. Calcar Cl. 



— coarse, — — sigmoid U. notata Pet. 



I Median line straight 5. 



4. { . .. 



I — — sigmoid I. 



I Median line reaching to the margin 6. 



' ■ 1 — — not C. molesta Ktiiz. 



J Stria; of the upper valve fine (20 in 0,0 1 mm.) C. finmarcliica Gbun. 



■ \ — — — — coarse (8 — — ) C. septentrionalis Geun. 



_ . Marine haliitat C. dirupta Gheg. 



Fresh water habitat 8. 



loculi. 



j Axial area dilated in the middle ■....('. minufa Cl. 



■ \ — — not — — — C. Jlexella Breb. 



') In the collection of E. Gkove I have seen some speeimens of C iVirnpta from Australia which had rndimentary 



