— 156 — 



of N. formica Htz. shows a narrow smooth longitudinal line and that it 

 perhaps is therefore not identical with N. Jelen. Grun. , which has a 

 longitudinal plication. The specimens examined by me have a sharp 

 plication along which the striæ pass, but with moderate magnifying power 

 the striation along the plication is not always easy to see, it therefore is 

 possible that this striation has escaped the attention of Hantzsch. 



Area for N. formica: East Indian Archipelago. 



Vivaces Grun. 



244. N. flumineiisis Grun. V. H. Syn. tab. LXII, figs. 3 — 4. 

 KKm, KKt, KMn-CLt (4 samples). 



Area: Gampeachy Bay, Mediterranean, Adriatic, Ceylon, Borneo, Malay 

 Archipelago. 



Spathïdatœ Grun. 



245. N. distans Greg. V. H. Syn. tab. LXII, fig. 10. 

 KCn s. 1. (2 samples,). 



Area: Europe, Bali Sound, Pacific Ocean. 



— — var. tumescens Grun. V. H. I.e. fig. 17. 



KKm, KKt (3 samples). 



Area: Gampeachy Bay, Mediterranean. 



246. N. angularis W. Sm. Perag. Diat. de Fr. tab. LXXIII, fig. 6. 

 KKm, KKt, KMn-CLt (4 samples). 



Area: ubiquitous. 



Sigmoideœ Grun. 



247. N. macilenta W. Sm. V. H. Syn. tab. LXIV, figs. 6-7. 

 KKm, TK (2 samples). 



Area: Europe, Ceylon. 



Sigmata Grun. 



248. N. Sigma W. Sm. var. rigida (Ktz.) Grun. V. H. Syn. tab. LXVI, 

 fig. 5. 



KKm, KKt (3 samples). 



Area: the main species ubiquitous. 



var. rigida: cum specie passim (de Toni). 



In a sample from KKt I found a small form belonging to the form- 

 circle of N. Sigma with L. 0,048 mm., b. 0,006 mm., carina! puncta 10 

 in 0,01 mm. Striæ not visible. I consider it a dwarf-form of N. Sigma 

 var. rigida, as it is too broad to be referred to var. rigidula. 



