GRAMMA! OPHORA. 355 



var. subtilissima Bailey. 



Valves somewhat attenuate between the median portion and the apices. 

 Striae 34 to 36 in 1 c.d.m. Length of valve, *6 c.d.m. ; breadth of 

 frustule, ri to 1*4 c.d.m. Breadth, i*i to 1*4 c.d.m. 



This form belongs to South America ; we notice it here because it is frequently employed 

 as a test object. 



G. angulosa Ehr. (Ktitz. Baa, pi. 29, f. 79*), plate 31, fig. 



862. 



Valves elongate, with rounded apices ; striae 13 to 14-5 in 1 c.d.m., cutting 

 one another at right angles. Girdle face showing septa, having one to four 

 undulations. Breadth of valves, about -5 c.d.m. Length, i"5 to 5-5 c.d.m. 



Marine. This species, which Grunow describes as widely dispersed, has not yet been found in 

 Belgium. Coasts of the North Sea, etc. 



var. hamulifera Kutz. (H.V.H. Atl., pi. 53, f. 4*; Type No. 351), 

 plate 11, fig. 481a. 



Apex of undulations forming an acute hock towards the connecting 

 zone. 



G. serpentina (Ralfs.) Ehr. (Ber., i8 44; h.v.h. Atl., pi. 



53, f. 1, 2, 3* ; Type No. 350), plate 11, fig. 482,7. 



Valve sub-elliptic ; striae about 17 in 1 c.d.m., formed of puncta arranged 

 in quincunx. Girdle face showing one (in very small forms) to four undulations, 

 the final one terminated by an acute hook. Distinguished easily from the 

 preceding species by the arrangement of the puncta. Breadth of valves, 

 about 1-5 c.d.m.; breadth of girdle face, 3 to 4 c.d.m. ; length of same, 2-5 

 to 15 c.d.m. 



Marine. Scheldt. (P. Gaut. and H.V.H. ). Very rate, Blankenberghe (H.V.H. ). England 

 (Comber, Stolt., Norman, Ralfs.), Scotland (Hennedy), Ireland (W. Sm.), and on all the coasts of 

 Europe. 



var. pusilla. (Gr. pusilla Grev.) differs from the type-form by the 

 undulations which are less marked, and only 2 or 3 in number ; by the 

 hook which is obtuse, and by the striae which are finer and 22 or 23 in 

 1 c.d.m. 



Marine. Scotland (Gregory). 



