16 p. T. CLEVE. ON SOifE NEW DIATOMS. 



This form has the appearance of S. Smithii Gron., but is larger and has coarser 

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



Schizostauron Grun. 



1. Schizostauron Crudcula Grun. 



Strite oblique, fine, 25 in 0,01 mm. Stauros bifid with very divergent branches, 

 reaching the margins. 



Length 0,03 mm. Breadth 0,009 mm. 

 PL in, fig. 44, ^"""A- 



Merrimac River U. St. on Chara, very rare in a gathering sent by Mr. 0. Nord- 

 STEDT. *) 



Nitzschia W. Sm. 



L Nitzschia ocellata Cl. 



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

 frustule is panduriform; the keel central Avith 8 10 puncta in 0,01 mm. The strite 

 are fine, 22 in 0,01 mm. composed of small, elongate puncta. The strice 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, b. frustle. 



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



This species is placed by Grcnow in his section Pseudoamphiprora, very nearly 

 to Perrya Kitton. 



2. Nitzschia prcelonga Cl. 



This species has already been described in Cl. et Grun. Arct. 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 stri* are strong, 

 16 in 0,01 mm. 



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

 PI. IV, tig. 48, a. ""/x, b. """>u- 



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



') In printing this paper I have been informed by Mr. Grunow that he has found the same form abun- 

 dantly in pools of the Rio Purus, Brazil, and that he has named it in Linuaean Society Journ. of May 1880 

 I consequently adopt his name. 



