4() r. T. CLEVE, .SYNOPSIS OF THE XAVICULOIl) DIATOMS. 



and obi. striiB 2*,.,.,, •-^.^, in 0,oi mm. — i)Ox\K. T. M. 8. p. 21 PI. ill f. 2. V. H. Syn. ]>. 114 

 PI. XVII f. 10. Per. IX f. 18, 19. 



Marine: Coasts of Scotland and England! Belginm (V. H.)I Balearic Islands! Sumatra 

 (Deby Coll.)! 



Var. madayascaroisis Grun. (iSiH). — Dorsal margin concave. L. 0,oi 7 ; P. 0,03 mm. Median 

 line close to the dorsal margin. Transv. and obi. stria' -"/ig in 0,oi mm. — T. madcui. Per. \). 28 

 PI. IX f. 13. 



Marine: Madagascar (Per). 



Var.? iDiflulatn Norm. (1861). — Dorsal margin gibbous in the middle, ventral triundulate. 

 L. 0, i."!; B. 0,032 mm. Transv. and obi. striit -" ,„ in 0,oi mm. — T. uiulnlata Prit. Inf. p. 920 

 PI. VIII f. 46 (1861). Per. IX f. 12. 



Marine: North Sea (Norm.). 



T. insiynis seems to graduate into T. Grcf/oriana. 



2. T. (iregoriana Donk. (1858). — V. linear to semilanceolate, with unilaterally rounded 

 ends, curved in the same direction. Dorsal mai'gin straight, ventral slightly convex. L. 0,i3 to 

 0,2.5; B. 0,022 to 0,03 mm. Median line arcuate, at the ends coincident with the margins. Transv. 

 and obi. striiB ^o/^g, 21/.^^ i^^ 0,01 mm. — Donk. T. M. S. VI p. 19 PI. Ill f. 1. Per. IX f. 16. 



Marine: Coasts of Scotland and England! 



Var. halcancd Cl. (1878). — Dorsal margin slightly concave. L. 0,i7 to 0,22; B. 0,02 to0,o2,") 

 mm. Transv. and olil. stride 1'/,^, I'/jg in 0,oi mm. — T. hidcaricd Cl. M. D. 154. Per. IX f. 14, 15. 

 Marine: Mediterranean Sea! 



3. T. Challengerensis Castr. (1886). — V. linear, narrow, inflated in the middle and at 

 the ends. L. 0,3; B. 0,(iu4 mm. — Castr. D. Exp. Chall. p. 39 PL XXVI f. 14, 15. Per. IX f. 17. 



Marine: Tahiti (Castr.). 



Caloneis Cl. N. G. 



Valve usually convex, of various shape, linear, lanceolate, panduriform, rarely sigmoid and 

 asymmetrical. Stritu usuall}- parallel, and divergent in the ends (rareh' convergent), not distinctly 

 (rarely finely) punctate, crossed by one or several longitudinal lines, which in some species increase 

 to broad, lateral areas. Connecting zone not complex. 



This genus comprises the groups abhfeviecs, formosecs, limos(k'S and I in car ires of Navicula 

 in the synopsis of Van Heur'ck, as well as the quadrisoiatce of Grunow. All these groups are 

 intimately connected, however dissimilar the outline of the different species may be. Smaller 

 forms of Caloneis with indistinct longitudinal lines closely resemble small Pinnulariu', and certain 

 of the panduriform species seem to be very closely connected with some marine, panduriform 

 Pinnulariee. 



Pfitzer, who has examined the cell-contents of C. Si licit la places this specis in his genus 

 Ncidium, but it has no near affinity with that genus. According to Pfitzer (Ban und Entw. p. 39) 

 there are as in Neidium two chromatophores, lying closely along the inside of the connecting zone, 

 which do not migrate to the valves, but are divided in situ by fissures parallel to the longitudinal 

 axis of the cell. It thus appears that there are interior characteristics also, which distinguish 

 Caloneis from Navicula. — The cell-contents (of C. blunda, C. Liher and C. fonnosa) have also two 

 chromatophore-plates along the connecting zone. Their margins are entire. 



The form of the valve is as a rule linear, or lanceolate, and straight. A sigmoid species, 

 C. stanrophora, has hitherto been regarded as a Plcurosicfma. This species has the ordinary form 

 of a Pleurosigma, but the following important characteristics induce me to place it in Caloneis: 



