ill!Ill

394
NITZSCHIA.
Differs from the preceding species by the apices of the keel, which are
much enlarged and elevated. Carinal dots 4 or 5 in 1 c.d.m. Strise
excessively delicate. Length, about 10 c.d.m.
Marine Blankenberghe, Antwerp (Scheldt H.V.H.), France (Br6b.), Denmark (Heib. !),
England (Harrison, Norman), Ireland (O'Meara).
var. hyalina (H.V.H. Atl., pi. 62, f. 9*), plate 16, fig. 524.
Very small (about 4 c.d.m.), about Same habitat.
7
or 8 carinal dots in 1 c.d.m.
N. distans Greg. (Diat. of Clyde, p. 58, pi. 6, f. 103; H.V.H.
Atl., pi. 62, f. 10*), plate 33, fig. 878.
Valve narrowly lanceolate, with apices somewhat produced, sub-rostrate ;
keel central with dots unequally distant, 1*5 to 3 in 1 c.d.m. Stria; excessively
delicate and approximate. Girdle face linear, with sub-truncate apices,
showing the keel somewhat alate. Length, up to 15 c.d.m.
Marine. England (Stolt.), Glenshira sand, Scotland (Gregory), Bahnsie (Lagerstedt).
N. cursoria (Donk.) Grun. (Arct. Diat, p. 89; H.V.H. Atl.,
pi. 62, f. 19* ; Bacittaria cursoria Do/ik.,) plate 33, fig. 879.
Valve very narrowly lanceolate, with apices longly rostrate, keel central,
narrow, with about 10 dots in 1 c.d.m., accompanied by two accessory lines,
distant about -4 c.d.m. Striation very fine. Frustule linear, with truncate
apices. Length, 7 to 8 c.d.m. Breadth of valve, 7 c.d.m.
Marine. England (Donkin, Norman), France (Brb.).
Group 15.
DlSSIPAT/E.
Differs from the two preceding groups by the keel being less
central and the absence of auxiliary lines. Valves very small and
very delicately striated.
ANALYSIS OF SPECIES.
Keel not quite central. Valves very small and delicately striated . N. dissipata.
N. dissipata (Kiitz.) Grun. ! (Arct. Diat, p. 90; N.
minutissima W. Sm. ? H.V.H. Atl., pi. 63, f. 1*; Type No. 391), plate 16,
fig- 525-