SYNDETONEl^. 



425 



Valve triangular with angles elevated, margin triundulate, without 

 indentations ; a rather short spine in the centre ; stria? radiant, very fine, about 

 20 in 1 c.d.m. at the margin of the valve. Frustules distant, united in a 

 filament. Length of side of frustule, about 6 c.d.m. 



Marine. Very rare. Blankenberghe, 2nd Basin. 



Note. These two Dityhim are probably forms of a single species. 



GENUS 91. SYNDETONEIS GRUN., 1888. 



ks&* 



}#i 



Valves dissimilar, with two marginal bid- 

 dulphiform elevations, and having in the centre 

 a long horn. 



The horn of one of the valves with its apex 

 dilated, somewhat bifid ; that of the other valve 

 bifurcate, clasping the horn of the other valve. 



The genus includes only a single form, S. 



amplectens (Gr. and Sturt.) Grnn., found in the 



Oamaru Deposit (New Zealand), and figured in the 

 margin. 



Fig. 142.- Syndetoneis 

 amplectens {Gr. and Stt/rt. 

 Grun. 



