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



striae are only slightly radiant, 6,5 to 7,5 in 0,oi m. m., crossed 

 by a band, occupying about a fourth of the length of the striae. 

 The raphe is generaly distinctly complex. The area is narrow, 

 and occupies about one fifth of the breadth of the valve. Typi- 

 cal specimens are 0,14 to 0,17 m. m. in length and 0,022 to 0,0 2 5 

 m. m. in breadth. 



Ab. 36, Lad. 86, Sb. 8, 10, 16, 21, Lt. 29, 30, 31, 32, Lim. 

 21, 23, 26. 



Foss. Nyl. 87, Sa. 88, 89, Ta. 94, 95, 96, 97, 98, Ob. 94, 

 95, Lk. 93, 104. 



Var. minor CI. — Smaller, 0,0 8 5 to 0,1 m. m. in length and 

 0,oi5 to 0,oi6 m. m. in breadth, raphe strongly complex, striae 

 slightly radiant 6 to 7 in 0,oi m. m., often interrupted on one 

 or on both sides of the central nodule. 



PI. 1, fig 2. 



Foss. Ta. 97, Lk. 93. 



Var. distinguenda CI. — Valve 0,10 5 to 0,18 m. m. in length. 

 Striae strongly convergent in the middle, divergent at the ends, 

 6,5 in 0,oi m. m. Area broad, about 1 / 3 of the breadth of the 

 valve. Raphe complex. 



This form, which perhaps may be admitted as a distinct 

 species, occurs often in slightly brackish water. It is found in 

 Sweden in the Karlshamn deposit together with Campylodiscus 

 Clypeus, in the Bory deposit of Hungary, in Northern America in 

 earths from Houghton (Michigan) and Sta Rosa (Calif.), in Austra- 

 lia at South Yarra and at Campbell Town in Tasmania. 



PI. I, fig. 1. 



Foss. Ob. 92, Lk. 104. 



Var. intermedia CI. — Valve 0,0 7 5 to 0,n m. m. in length 

 and 0,oi4 to 0,015 m. m. in breadth. Striae 9 in 0,oi m. m., 

 convergent at the midde and divergent at the ends. Raphe com- 

 plex. Area about a fourth of the breadth of the valve. 



A. S. XLII, 9, 11 (as Nav. major. The complex nature of 

 the raphe is not represented in these figures). 



Ab. 36, 49, Lad. 86, Sb. 2, 8, 10, 15, 16, Lt. 29, 30, 32, 33, 

 Lim. 20, 21, 23, 24, 26. 



Foss. Sa. 89, Ta. 95, 96, 97, 98, Tb. 90, Ob. 92, Lk. 93, 104. 



Var. commutata Grun. — A. S. XLV, 35. V. H. V, 6. 



