SCATOLOGICAL STUDIES OF THE BIVALVIA (RIOLLUSCA)
331
Locality : Mukaishima, Hiroshima, Japan.
Measurements : For an animal with a shell 180 mm high, average width
of the faecal ribbons is 2.07 mm.
49. Atrina pectinata japonica (Rve) (Pl. 1-11)
Ribbons of this species are discharged broken into much shorter
pieces. They have no grooves and ridges. Both free edges are thickened
and strongly turned dorsalwards. The dorsal surface is smooth in contrast to the ventral surface which is rather coarse and uneven (Pellettype 111-10).
Locality : Shirahama, Wakayama, Japan.
Measurements: Faecal ribbons shed by an animal of shell length
300 mm average 2.5 mm in width.
Ostreidae
Pellets of members of this family which have so far been examined
are, without exception, grooved ribbons bi-crescentic in section (Pellettype 111-l0a).
50. Ostrea edulis L. (PI. 2-12; Fig. 17, bottom, p. 400)
I n the faecal ribbons of this species, the mid-dorsal ridge is large and
prominent, and the mid-ventral groove is narrow but very deep. The
lateral wings are strongly upcurled. Thus, in transverse section, they
are bi-cricoidal rather than bi-crescentic. They are dark chocolate in
colour and smooth in surface texture, except over the median longitudinal ridge where the surface is coarse and uneven (Pellet-type
111-1 0a).
Locality : Miyagi Pref, Japan (immigrated from Europe).
Measurements : The width of the faecal ribbons fluctuates between
1-46 and 2.28 mm.
51. 0. densebmellosa futamiensis Seki (Pl. 5-55)
Faecal ribbons are very thin, rather coarse in consistency and pale
yellowish-brown in colour. They have a thickened mid-dorsal ridge.
Both edges of the ribbons are slightly thickened and turned (Pellettype 111-lOa).
Locality : Mukaishima, Hiroshima, Japan.
Measurements: For an animal with shell 40.0 mm long, width of the
ribbons fluctuates between 0.65 and 0.85 mm.
331
Locality : Mukaishima, Hiroshima, Japan.
Measurements : For an animal with a shell 180 mm high, average width
of the faecal ribbons is 2.07 mm.
49. Atrina pectinata japonica (Rve) (Pl. 1-11)
Ribbons of this species are discharged broken into much shorter
pieces. They have no grooves and ridges. Both free edges are thickened
and strongly turned dorsalwards. The dorsal surface is smooth in contrast to the ventral surface which is rather coarse and uneven (Pellettype 111-10).
Locality : Shirahama, Wakayama, Japan.
Measurements: Faecal ribbons shed by an animal of shell length
300 mm average 2.5 mm in width.
Ostreidae
Pellets of members of this family which have so far been examined
are, without exception, grooved ribbons bi-crescentic in section (Pellettype 111-l0a).
50. Ostrea edulis L. (PI. 2-12; Fig. 17, bottom, p. 400)
I n the faecal ribbons of this species, the mid-dorsal ridge is large and
prominent, and the mid-ventral groove is narrow but very deep. The
lateral wings are strongly upcurled. Thus, in transverse section, they
are bi-cricoidal rather than bi-crescentic. They are dark chocolate in
colour and smooth in surface texture, except over the median longitudinal ridge where the surface is coarse and uneven (Pellet-type
111-1 0a).
Locality : Miyagi Pref, Japan (immigrated from Europe).
Measurements : The width of the faecal ribbons fluctuates between
1-46 and 2.28 mm.
51. 0. densebmellosa futamiensis Seki (Pl. 5-55)
Faecal ribbons are very thin, rather coarse in consistency and pale
yellowish-brown in colour. They have a thickened mid-dorsal ridge.
Both edges of the ribbons are slightly thickened and turned (Pellettype 111-lOa).
Locality : Mukaishima, Hiroshima, Japan.
Measurements: For an animal with shell 40.0 mm long, width of the
ribbons fluctuates between 0.65 and 0.85 mm.