HELMINTHOPSIS. 



455 



Valve with ventral margin straight, dorsal margin undulate, furnished 

 with 6 to 14 transverse costal, finely stiiate, striae forming transverse lines, 

 17 to 21 in 1 c.d.m. Length, 275 lo 4/5 c.d.m. 



Marine. Ostend (Grunow). 



GENUS 120. HELMINTHOPSIS, H.V.H. IN LITT, 1892. 



a 



M 



Fig. 181. Helminthopsis 

 Weissflogii. 



Valve very elongated, with apices sub- 

 acute, curved in contrary directions, divided 

 by transverse septa into rounded compart- 

 ments. Surface punctate, with puncta small 

 but very conspicuous and scattered. 



This curious diatom, the name o! which reminds 

 one of its resemblance to an intestinal worm, was 

 found by Mr. Weissflog in the Oamaru Deposit where 

 it is very rare. I have dedicated it to my old and 

 excellent friend under the name of H. Weissflogii. 



GENUS 121. HEMIAULUS (Ehr., 1844), H.L. Sm. Emend. 



Valve punctate, often furnished with constrictions or interior costae, 

 median portion often inflated, furnished with processes, often elon- 

 gated, generally straight, placed on the outer margin in girdle view 

 and tipped with a spine or mucro, which is sometimes obscure. 



Heiberg created many different genera at the expense of Hemiaulus. 

 Prof. H. L. Smith in the first case, and Grunow afterwards, proposed to 

 restore Heiberg's genera to the original genus, and this I have done here, 

 while subdividing the genus into four sub-genera as follows : 



f f Valve elliptic, oval, or sub-lanceolate, furnished with two 



processes ....... Hemiaulus. 



Valve j 

 symmetrical. " Valve triangular, with three processes . . . Trinacria. 



(^ Valve quadrangular, with four processes . . . Solium. 



L Valve cuneale, with two processes, one of which much longer than the other Corinna. 



