16 P. T. CLEVE, ON SOME NEW DIATOMS. 



This form has the appearance of S. Smit/m Grun., but is larger and has coarser 

 stria^ (being 28 in 0,01 mm. on S. Smithii) not so parallel as in 5. Smithii. 



Scliizostauron Grun. 



1. Scliizostauron Crucicula Grun. 



Strias oblique, fine, 25 in 0,01 mm. Stauros bifid with very divergent branclies, 

 reaching the margins. 



Length 0.03 mm. Breadth 0,009 mm. 



Pl. III, fig. 44, ^"»Vi- 

 Merrimac River U. St. on Chara, very rare in a gathering sent by Mr. O. Nord- 



STEDT. ^) 



Nitzschia W. Sm. 



1. Nitzschia ocellata Cl. 



This species has already been described in Cl. et Grun. Aret. Diat. p. 80. The 

 frustule is panduriform; the keel central with 8 — 10 puncta in 0,01 mm.* The striaä 

 are iine, 22 in 0,01 mm. composed of small, elongate puncta. The strias are sharper 

 and more distant in the centre of the valve. The whole valve is covered with large 

 scattered puncta sometimes arranged in irregular, transverse lines. 



Length 0,08 — 0,1 mm. Breadth of the frustule 0,027 mm. at the constriction 

 0,018 mm". 



Pl. IV, fig. 47, '""Vi, a. valve, h. frustle. 



Balearic Islets (Dr. Söderlund), Cl. et Moll. Diat. N:o 154 — 155 rare. 



This species is placed by Grunow in his section Pseudoamphiprora, verj^ nearly 

 to Perrya Kitton. 



2. Nitzschia prcelonga Cl. 



This species has already been described in Cl. et Grun. Aret. Diat. p. 85. The 

 frustules are extremely long and slender, slightly arcuate, linear, with obliquely cuneate 

 ends. Keel almost central, with about 5 puncta in 0,01 mm. The stria^ are strong, 

 16 in 0,01 mm. 



Length 0,25 mm. Breadth 0,009 mm. 

 Pl. IV, fig. 48, a. '"/„ b. ""y,. 



Balearic Islets not rare (Dr. F. Söderlund). 



') In priiiting this paper I luive been informed by Mr. Grunow tliat. lie bas fouiid the same form abun- 

 (lantly in pools of the llio Piirns, Biazil, and that lie has nained it in Linintan Sociotv .lourii. ol' Mav 1880 

 I coiiseijucntly adopt his narac. 



