354 GRAMMATOPHORA. 



ANALYSIS OF SPECIES. 



( Puncta of valves arranged in rows cutting one another at right angles . G. ang'ulosa. 



I False septa strongly undulated throughout their length, 

 p terminating in an acute hook directed towards the con- 



unc a j necting zone . . . . G. serpentina. 



quincunx. , p a ] se se pt a only undulated at their origin, not terminating 



[ in an acute hook . . . . G. marina 



G. marina (Lyngb.) Kutz. (Baa, p. 128, pi. 17, f. 24; 

 H.V.H. Atl, pi. 53, f. 10 and 11*), plate 11, fig. 479. 



Valves elongated, linear, with rounded apices ; striae 18 to 21 in 1 c.d.m., 

 formed of puncta arranged in quincunx ; apices of valves smooth, without 

 any puncta. Girdle face broad, linear, elongated, with rounded angles ; false 

 septa at first straight, then broadly curved towards the interior, then becoming 

 again straight, and apparently terminating in a longitudinal thickening. Mean 

 length, 6 to 8 c.d.m. Breadth of valves attaining to 1*5 c.d.m. Breadth of 

 connecting zone, 3 c.d.m. 



Marine. The type-form (var. major Grun.) has not yet been found in Belgium. England 

 (Comber, Norman, Stolt. ), Ireland (W. Sm.). 



var. communis. (Gr. ocea?iica var. communis Grun. ; H.V.H. Type 



No. 355). 



Frustule and valve narrower than the type-form. Valve usually some- 

 what inflated at the median portion. Striae, 23 or 24 in 1 c.d.m. Breadth 

 of valve, "45 to '6 c.d.m. Length of fruscule, 2 to 7 c.d.m. ; breadth, 

 9 to 1 "4 c.d.m. 



Frequent in Europe, but not yet found in Belgium. 



var. vulgaris. (Gr. oceanica var. vulgaris Grun. ; H.V.H. Type 

 No. 356). 



Frustules and valves narrow ; valves usually somewhat attenuate 

 between the middle and the apices. Striae, 23 or 24 in 1 c.d.m. Breadth 

 of valve, -6 to "j c.d.m. Length of frustule, i*6 to 10 c.d.m. ; breadth, 

 1 '3 to 1 "6 c.d.m. 



Frequent in Europe ; Belgium. Nieuport (West.), Ostend (Ch. Petit.). 



var. macilenta. (Gr. macilenta IV. Sm., S.B.D., ii., pi. 61, f. 382 ; 

 H.V.H. Atl., pi. 53 bis, f. 16* ; Type No. 353), plate 11, fig. 480^. 



Girdle face and valves very narrow ; valves gently attenuate between 

 the median portion and the apices; striae 23 to 31 in 1 c.d.m. Breadth 

 of valve, '4 to - 6 c.d.m. Breadth of girdle face, - 8 to 1*5 c.d.m. ; 

 length, 1-5 to 10 c.d.m. (Grun.). 



Marine. Washings of mussels (Deby), England. 



