UTRECHT MICROPALEONTOLOGICAL BUllETINS

it is not thickened towards the rim of the basal cavity, Lindstrom's (1971)
suggestion, to consider this genus as part of this "Panderodids" (Lindstrom,
1971, p. 49-51) will not be followed.
Stolodus stoIa (LINDSTROM), emend. LINDSTROM, 1971
(PI. 8, figs. 20-24)
Distacodus stoia LINDSTROM, 1955a, p. 556, PI. 3, figs. 43-49.
Distacodus stoia latus LINDSTROM, 1955a, p. 557, PI. 3, figs. SO, 51.
Coelocerodontus stoia (LINDSTROM). LINDSTROM, 1964, p. 84, fig. 29.
Stolodusstola (LINDSTROM). LINDSTROM, 1971, p. 51.
Remarks: The illustrations show the extreme fragility of all elements. Their
colour is white and they are translucent if moistened. The basal sheath and
the keels are very thin, the cusp usually is broken. In addition to symmetrical
distacodiform elements there are two different types of asymmetrical
form variants, with elongated bases.
In one of these variants (PI. 8, figs. 22a, b), one side has a costa which is
confined to the cusp; the anterior and posterior keels are deflected to the
same side of the unit. A costa of the opposite side runs from the cusp all
over the base to reach the aboral margin. To this side of the unit an
additional costa is confined to the oral-lateral side of the base. Through this,
the cross section of the base is approximately an equilateral trapezium with
the parallel sides in vertical position.
In the other asymmetrical element (PI. 8, figs. 21a, b) the basal stretches
of the anterior and posterior keels are twisted relatively to the cusp as well as
to the lateral costae. As a consequence, the anterior and oral keels are
situated close to the lateral costae and the anterior and oral sides are flat
basally. The cross section of the base is' approximately a parallelograrrt with
the largest laterals oriented orally and antero-basally.
Nothing needs to be added to the original description of the symmetrical
distacodiform elements (PI. 8, figs. 20 and 24).
PI. 8, fig. 23 shows that the keels can have denticle-like modifications.
Such elements resemble similar elements of the species Prioniodus deltatus
(LINDSTROM), emend. herein (PI. 8, figs. 5a, band 7). The elements of
Stolodus stola are much more fragile, they are coloured more intensely
white, they have thinner keels and basal sheaths and a different intraspecific
symmetry-variation of the elements.
Regional occurrence: At Kopingsklint this species occurs from the base of
member Kk3 up to a level at about 0.70 m. above the base of the Bruddesta
Formation. In section 6 from the top of member Ka-d1 up to a level at
about 1.20 m. above the base of the Bruddesta Formation. Near Horns Udde