ill!Ill

336
DIMEREGRAMMA.
ANALYSIS OF SPECIES.
'
Valve more or less broadly lanceolate ; pseudo-raphe lanceolate . . D. minor.
[ pseudo-raphe
Valve linear f
or narrowly Valve not inflated at the median portion ; puncta tine . D. fulvum.
lanceolate ;
J
"1
linear, Valve somewhat inflated in the middle ; puncta robust . D. marinum
narrow (,
D. minor (Greg.) Ralfs. (Greg. Diat. of Clyde, p. 23, pi. 2, f.
35, sub Denticula; H.V.H. Atl., pi. 36, f. 10 and iifl*), plate 10, fig. 392.
Valve lanceolate, with apices obtuse, smooth ; pseudo-raphe very gently
dilated towards the median portion; striae 10 in 1 c.d.m. formed of well
marked puncta, rather distant, not forming longitudinal lines. Frustules
quadrangular, attenuate underneath the apices,
Length, 3 to 4 c.d.m.
which are obtuse-truncate.
Marine. Blankenberghe, Ostend. Scotland (Lamlash Bay and Loch Fyne, Greg. ! Cumbrae,
sand washings, Baxter Coll., No. 2478.
Ireland (O'Meara).
var. nana. (Denticula nana Gre*., Diat. of Clyde, p. 23, pi. 2, f. 34;
H.V.H. Atl., pi. 36, f. wb, 12, and 13*), plate 11, fig. 393.
Valve inflated at the median portion, with apices abruptly attenuate;
but shorter.
stria? 14 in 1 c.d.m. ; girdle face as in the type-form,
1 to 2 c.d.m.
Length,
Marine. Blankenberghe, Ostend. Mixed with the preceding. England (Stolt.),
Scotland.
D. fulvum (Greg. !) Ralfs. (in Pritch. Inf., p. 790; Denticula
fulva Greg. ! ; H.V.H. Atl, pi. 36, f. 7*), plate 30, fig. 849.
Valve very narrowly linear, with apices gently capitate, rounded ; striae
about to in 1 c.d.m., distinctly granular. Girdle face rectangular, narrow.
Length, 4 to 7 c.d.m.
Marine. Scotland (Lamlash Bay, Greg. !), Ireland, Sweden.
D. marinum (Greg. !) Ralfs. (in Pritch. Inf., p. 790; Denticula
marina Greg. ! ; H.V.H. Atl., pi. 36, f. 9*), plate 30, fig. 849 bis.
Valves lanceolate, linear, gently inflated at the median portion, with apices
obtuse, rounded. Raphe rather broad, lanceolate, somewhat dilated at the
median portion, terminated by rounded smooth spaces. Stria;, 4 in 1 c.d.m.,
formed of very coarse puncta. Girdle face rectangular, very narrow, some-
what attenuate near the apices. Length, 8 to n c.d.m.
Marine. English Channel (Temp, and Perag., No. no). Scotland (Lamlash Bay, Greg. !)
Ireland (O'Meara).