KONGL. NV. VET. AKADEMIEN.s II AM>LIN(;AK. BAMJ 26. N:() 2. 4.') 



4(i. P. foniiosmn W. Sm. (1852). — V. narrow, linear-lanceolate, gently sigmoid, gradually 

 and unilaterally narrowed towards the eiuls. L. U,i4 to 0,5;!; H. 0,02 to 0,or, mm. ]\Iediaii liiii' 

 sigmoid, excentric, generally for a considerable distance coincident with the convex margin. ()l)li((ue 

 striae crossing each other at an angle of 90°. Transv. and ohl. stri.c '*,',„, '7i4' ""/16 inO,oi mm. — 

 W. Sm. Aim. M. Nat. H. [2] IX p. 5 PI. If. 1. li. 1). p. (J^ PI. XX f. 195. Grun. A. D. p. 48. 

 V. H. Syn. p. IlC PI. XIX f. 4. Per. 1 f. H to a. F. amtralicum O. Witt. Mus. Godetf, p. 70 

 PI. VIII f. 7 (1X73). F. (krorum. A\'. Sm. I p. 63 PI. XXI f. 19(). Grun. A. I), p. 49. V. H. Syn. 

 p. 11(5 PI. XIX f. 1. Per. I f. 11 to 13. F. tahitmsc U. Witt. Mus. Godetfr. p. 07 PL VII 1 

 f. 13 (1S73). 



]\larine: North Sea! J^fediterranean Sea! lied Sea! Java! China! Behrings Island! Sandwichs 

 Islands! Gala^jagos Islands! West Indies! 



Var. dalmutica Grun. (1880). — V. narrow, slender, acute, slightly sigmoid. L. 0,2.5 to 0,32; 

 B. 0,(i:! mm. Median line slightly excentric. Transv. and obi. strite '^/|2) '7i4 i^^ **'"' i"^- — 

 F. decor, var. dalm. Grun. A. I), p. 49. Per. II f. 6 to 9?. Icon. n. Pi. IV f. 21. 



Marine: Balearic Islands! Adriatic (Grun.)! 



Var. (Ehoicosigma) Arcus Cl. — V. arcuate. L. 0,2; B. 0,02 mm. Transv. and obi. stride '7i3 

 in 0,01 mm. — PI. IV f. 18. 



Marine: Macassar Straits (Grove Goll.)! 



Var. halearica Per. (1891). —V. linear, with unilaterally rounded ends. L. 0,35 to 0,54; B. 

 0,034 to 0,06 mm. Transv. and obi. stria* '-'/g, ■''/.j, '79 in 0,oi mm. — Per. p. 4 PI. I f. (i, 7. 



Marine: Mediterranean Sea (Per.), Singapore (Grove Coll.)! 



Var. lonciissima Grun. (1880). — V. lanceolate, sigmoid. L. 0,4 to 0,78; B. 0,o85 to 0,073 mm. 

 Median line sigmoid, excentric at the ends. Transv. and obi. striae '^/m, '*/,,, 'Vii, 'Vui 'Vi:i in 

 0,01 mm. — Grun. A. D. p. 48. Per. p. 4 PL I f. 1, 2. 



Marine: Puerto Caballo (Per.), Colon! Campeachy Bay! Samoa! China! Java! Galapagos 

 Islands! 



All the forms from F. spcciosum are very nearly connected and might be united into one 

 single species, characterized by the oblitpie striiv crossing each other at an angle of about 90°. 

 Between F. fornto.siini and F. decorum there is absolutely no specific difference, and by numerous 

 varieties P. formosam graduates into F. pnJchrHm and F. speciosuni. By the var. dcdmatiea F- 

 formosum is connected with F. .mhriqidutn, F. lon</ii)ii and F. Feruf/alli, which latter is intermediate 

 in the passage to F. NuhecuJa. ■— Donkinia reticidala Norm. (Grev. in T. Bot. Soc. Ed. vol. VIII 

 p. 237 PL 111 f. 13, 14. Pritch. Inf. 1861 p. 921) is probably akin to the last described species. 

 It is a large form (L. 0, 16 mm.) with very excentric median line and highly carinated valves. 

 Oblique strife about 8 in 0,oi mm. This form, found in Western Australia, is entireh' unknown 

 to me. A somewhat similar form occurs in Oamaru deposit but I have seen only some incomplete 

 specimens. L. 0,2. Striic 10 in 0,oi mm. 



Toxonidea Donkin (I808). 



Valve asymmetrical, thin. Median line arcuate, excentric. Axial area indistinct. Central 

 area indistinct. Structure the same as in Pleurosigma. Zone not complex. 



This genus comprises ai^ymmetrical forms of Pleurosigma. The cell-contents are not known, 

 but will probably offer some interesting peculiarities. 



1. T. inslgnis Donk. (18r)8). — V. strongly asymmetrical, with almost straight dorsal and 

 very convex ventral margin. Ends subrostrate. L. 0,12 to 0,1.3; B. 0,o2.t to 0,03 mm. Median 

 line strongly excentric, coincident at the ends for some di.^tance with the dorsal margin. Transv. 



