38 Acta Societatis pro Fauna et Flora fennica, VIII, n. 2. 



N. fontinalis Grun. — V. H. XII, 33. 

 Sb. 5. 



Foss. Sa. 88. 



One specimen from Savitaipale is 0,0 2 5 m. m. in length, 0,-0 6 

 m. m. in breadth, and has 23 striae in 0,oi m. m. 

 N. Schumanniana Grun. — V. H. XI, 21. 

 Lad. 85 (rare). 



N. silicula Grun. — V. H. XII, 21. 

 Lirn. 26, Li. 29, 32, 34, 35. 

 N. gracillima Greg. — V. H. VI, 24. 

 Ab. 36, Sb. 3, 4, Lt. 31, Lira. 21, 22, 23. 

 Foss. Sa. 88, Lk. 93. 



Neidium Pfitzer. 



The species belonging to Neidium form together a very na- 

 tural and well limited group of forms so closely connected, that 

 it is exceedingly difficult to distinguish the species. The charac- 

 teristics of Neidium consist in the arrangement and division of 

 the endochrome, described by Pfitzer 1 ), the opposite directions 

 of the interior ends of the median lines, the peculiar structure of 

 the endpores, and the structure of the valve. The puncta of the 

 valve form longitudinal and transverse, often oblique lines, which 

 are interrupted by one or more longitudinal lines. In the arran- 

 gement of the endochrome, and to a certain extent in the struc- 

 ture of the valve Neidium comes near to the limosae-group of 

 Navicula. 



N. Iridis Ehb. — V. H. XIII, 1. — A. S. XLIX 2, 3. 



Ab. 37, Al. 59, Kon. 43. 



Foss. Ob. 92, Lk. 93, 104. 



N. amphigomphum Ehb. — A. S. XLIX, 31, 32, 33, 34. 



Al. 59, Ab. 37. 



Foss. Sa. 88, 89, Tb. 90. 



N. dilatatum Ehb. — A. S. XLIX, 6. 



Ab. 36. 



Foss. Sa. 89, Tb. 90. 



N. dubium Greg. — V. H. Suppl. B 32, A. S- XLIX, 11, 24. 



x ) Unters. uber. d. Bau unci Entw. der Bacillarieen 1871, p. 39. 



