356
KOHMAN Y . ARAKAWA
is normally smooth but occasionally this is marked by faint spiral
striae. The ratio of length to breadth of pellets averages 2-61 (Pellettype 1-2).
Locality : Kaita Bay, Hiroshima, Japan.
Measurements when size of producer is unknown :
Length of pellet (mm)
Breadth of pellet (mm)
Ratio length/breadth
1.13 1.20 1.37 1-33 1.66 1-55 1-02 1.40 1.77
0.55 0.49 0.51 0.51 0.55 0.49 0-56 0.55 0.56
2.05 2.45 2.74 2.66 3.02 3-16 1.82 2.55 3.16
Remarks : One animal collected at Shikanoshima, Fukuoka, Kyushu,
produced rod-shaped pellet with coarse texture, measuring 0.50 mm in
breadth. This pellet was formed almost entirely from undigested matter
and some sand grains ; it seemed to ‘be atypical.
Semelidae
Members of this family may produce either discoid (Pellet-type
I-la), ovoid (1-1) or ellipsoid pellets (1-2). In general appearance, the
pellets resemble each other, but they may be separated by examination
of the lengthlbreadth ratios.
125. Abra alba (Wood)
“ The pellets are extremely uniform in shape, parallel-sided with
rounded ends and circular in section ; the surface is smooth and regular ;
the usual breadth is 0-25 to 0.3 mm, and the ratio of length to breadth
about 1.75.” (Moore, 1931a, p. 363, Figs. 1 and 5, B.) (Pellet-type 1-1).
126. A . nitida (Miiller)
“Much less regular in form than S. alba, and frequently either
tapered at one end or constricted at one or more points; surface
smooth; narrower than S. alba, breadth 0.2 to 0.25 mm.” (Moore,
1931a, p. 363, Figs. 2 and 5, C, D, and E.) (Pellet-type 1-1).
127. Abrina Zunella (Gould) (Fig. l l ~ )
voided together in strings.
(Pellet -type I- 1 a).
Locality : Hiroshima Bay (20 m in depth), Hiroshima, Japan.
Faecal pellets of this species are disc-shaped and are, at times,
Ratio length/breadth of pellets is 0.61
KOHMAN Y . ARAKAWA
is normally smooth but occasionally this is marked by faint spiral
striae. The ratio of length to breadth of pellets averages 2-61 (Pellettype 1-2).
Locality : Kaita Bay, Hiroshima, Japan.
Measurements when size of producer is unknown :
Length of pellet (mm)
Breadth of pellet (mm)
Ratio length/breadth
1.13 1.20 1.37 1-33 1.66 1-55 1-02 1.40 1.77
0.55 0.49 0.51 0.51 0.55 0.49 0-56 0.55 0.56
2.05 2.45 2.74 2.66 3.02 3-16 1.82 2.55 3.16
Remarks : One animal collected at Shikanoshima, Fukuoka, Kyushu,
produced rod-shaped pellet with coarse texture, measuring 0.50 mm in
breadth. This pellet was formed almost entirely from undigested matter
and some sand grains ; it seemed to ‘be atypical.
Semelidae
Members of this family may produce either discoid (Pellet-type
I-la), ovoid (1-1) or ellipsoid pellets (1-2). In general appearance, the
pellets resemble each other, but they may be separated by examination
of the lengthlbreadth ratios.
125. Abra alba (Wood)
“ The pellets are extremely uniform in shape, parallel-sided with
rounded ends and circular in section ; the surface is smooth and regular ;
the usual breadth is 0-25 to 0.3 mm, and the ratio of length to breadth
about 1.75.” (Moore, 1931a, p. 363, Figs. 1 and 5, B.) (Pellet-type 1-1).
126. A . nitida (Miiller)
“Much less regular in form than S. alba, and frequently either
tapered at one end or constricted at one or more points; surface
smooth; narrower than S. alba, breadth 0.2 to 0.25 mm.” (Moore,
1931a, p. 363, Figs. 2 and 5, C, D, and E.) (Pellet-type 1-1).
127. Abrina Zunella (Gould) (Fig. l l ~ )
voided together in strings.
(Pellet -type I- 1 a).
Locality : Hiroshima Bay (20 m in depth), Hiroshima, Japan.
Faecal pellets of this species are disc-shaped and are, at times,
Ratio length/breadth of pellets is 0.61