232 



SCH1Z0NEMA. 



Valve excessively small, elliptic lanceolate, with apices obtuse rounded. 

 Striae radiant, almost straight, reaching to the raphe, 20 or 21 in 1 c.d.m. 

 Length, 1 c.d.m. Breadth, about 0-25 c.d.m. 



Marine. Coasts of Northern Europe. 



II. Stauroneidese. 



N. (S.) crucigerum W.Sm. ! (S.B.D., ii., p. 74, pi. 56, f. 354, 

 and pi. 57, f. 356; H.V.H. Atl., pi. 16, f. 1*; Type No. 151), plate 5, 

 fig. 242. 



Valve lanceolate acute ; central nodule prolonged up to the margins of the 

 valve into a stauros, which is covered with two striae more robust than the 

 others. Striae reaching almost to the raphe, 24 in 1 c.d.m., almost parallel, 

 finely divided transversely, with divisionj simulating delicate longitudinal 

 striae. Length, about 7 to 8 c.d.m. Breadth, about 1 c.d.m. 



Marine. Scheldt at Antwerp. Blankenberghe. England, Scotland, Ireland. 



The photograph has not reproduced the stauros as it is found in the 

 original figure. In the figure in my Synopsis the valve appears without a 

 stauros. 



III. Perstriatae. 



N. (S.) Grevillei Agardh. (Consp., p. 19; H.V.H. Atl., pi. 16, 

 f. 2*; Type No. 152), plate 5, fig. 243. 



Valves rather broadly lanceolate, with obtuse apices ; striae reaching almost 

 to the raphe, strongly punctate transversely, the 3 or 4 median ones straight, 

 very distant, the others approximate, about 20 in 1 c.d.m., gently radiate up to 

 the apex of the valve. Girdle face quadrangular, with rounded apices, com- 

 pressed at the median portion ; connective membrane with numerous longitu- 

 dinal striae. Length, 3 to 7 c.d.m. Breadth, about 1*5 c d.m. 



Marine. Ostend (Weslendorp, n. 896 and 897), Blankenberghe. England, France, Denmark, 

 Heligoland. 



Later researches, after the publication of the Atlas to my Synopsis, has 

 proved that the JS'avicula J)elognei (pi. n, f. 13) ought to be considered as a 

 form of S. Grevillei. 



N. (S.) ramosissimum C. Agardh. (Consp., p. 22; H.V.H. 



Atl., pi. 15, f. 4*; Type No. 153), plate 5, fig. 244. 



