KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 18. N:0 5. 11 



This small species seems to be the unnamed form in A. Schmidts Atlas Pl. 46, fio;. 7 

 and is perhaps according to Gkunow the M. mediterranea Kutz. Bac. Pl. III, lig. XVII, 

 which however is represented on much too small a scale to admet of identilication. 

 Another allied form is the yet unpublished N. cotiformis Grun. from Demerara River, 

 which has cuneate ends and 5 strise in 0,01 ram. Length 0,06 mm. Breadth 0,014 mm. 



16. Navicula Anderssonii Cl. N. Sp. 



Linear oblong, with almost cuneate ends. Strins parallel or slightly radiate in 

 the middle, 6V2 — 7 in 0,01 mm. not reaching the median line, which in surrounded by 

 a narrow area, dilated around the central nodule. 



Length 0,075 mm. Breadth 0,019 mm. 

 Pl. III, lig. 28, "°7i. 



Gallapagos Islands (Eugenie Exp.). 



I have named this species in honour of the late Prof. N. J. Andersson, botanist 

 to the Eugenie Expedition. 



17. Navicula margimdata Cl. N. Sp. 



Rhombic; striaj very short, marginal, enclosing a large structureless area, 17 in 

 0,01 mm. 



Length 0,042 mm. Breadth 0,012 mm. 



Pl. III, fig. 29, ^""Vi- 

 Florida, near the Harbour of Pensacola, in a gathering sent by Mr. Febiger. 



18. Navicula (Poioelli Lewis var.) Gallapagensis Cl. 



Linear oblong with cuneate ends. Stria3 coarse, almost parallel, 8V2 in 0,01 mm., 

 on both side of the median line interrupted by linear areas. There are thus four lon- 

 gitudinal series of short strise, two near the margins and two close to the median line, 

 interrupted near the central nodule. 



Length 0,05—0,09 mm. Breadth 0,013—0,021 mm. 



Gallapagos Islands (Eugenie Exp.). 

 Pl. III. fig. 30. 



Of the true N. Poioellii Lewis I have not seen a figure, but Grunow states that 

 his N. Vidowichii (Verh. 1863, Pl. IV, fig. 4) is the same species. I have seen the latter 

 form in gatherings from Adriatic sea, kindly sent me by Mr. F. Hauck, and I lind 

 that the form is different, the striaa more distant (6 in 0,01 mm.). Length 0,1122 mm. 

 Breadth 0,02 mm. N. Egyptiaca Grev. Träns. Micr. Journ. XIV, p. 127, Pl. 12, lig. 

 16 — 17 seems to be the same, but the strias are stated to be only 4 in 0,01 mm. An- 

 other allied form is, as far on may judge from the figure, N. Zanardiniana Grun. 

 (Verh. 1860, Pl. 3, fig. 12) with indistinctly punctate striae, 6 in 0,01 mm., in four 

 uninterrupted rows. Another, undescribed form is N. Wittii Grun. Mspt. (Pl. Ill, fig. 

 31, ^"Vi) from Brazil, which is not so long and slender as the last named species and 

 has 8 stria3 in 0,01 mm: The two foUowing forms are also allied to N. Powellii. 



