316
ICOHMAN Y. ARAICAWA
IIA. ROD-RIBBON
Pellet-type 9. Rod with a trefoil-shaped section
The pellets belonging to this type consist of a rod which is trilobed
in section. Of the three longitudinal ridges, the median one is fine in
texture with the surface occasionally broken by transverse clefts, while
the other two have a smooth but rather coarse surface. The depth and
position of the exterior grooves vary according to species. This type of
pellet is peculiar to species of Chlamys in the Pectinidae (Gastrotetartika).
Pellet-type 9a. Rod with a triangular section
Moore (1931a) examined pellet-type 9a in Chlamys triradiata
(Muller) (erroneously described as Pecten septemradiatus) and noted that
this type of pellet consists of a triangular-sectioned rod with rounded
margins, one being sharper than the other two, and with slightly concave sides.
111. RIBBON
Ribbon-like pellets are probably defecated by all of the Gastrotriteia and some of the Gastrotetartika, and can be classed under two
distinct types according to whether or not they are grooved. On the
whole, ribbon-like pellets are morphologically unstable, because the
form of the post-intestinal lumen tends to be affected by the dietetic
or physiological conditions of the animal.
Pellet-type 10. Ungrooved ribbon
This type of faecal ribbon is normally slightly curved and crescentic
in section and may be produced by a wide major intestinal typhlosole.
Pellet-type 10 probably occurs in nearly all of the Gastrotriteia and
some of Gastrotetartika, namely Arcidae, Pteriidae, Glycymeridae,
Pinnidae, Plicatulidae, Unionidae, Carditidae, Anomiidae and ZSpondylidae.
Pellet-type 10a. Grooved ribbon
This type of pellet possibly occurs in four families of the Gastrotriteia, namely Mytilidae, Ostreidae, Isognomonidae and some of the
Pectinidae. It can be distinguished from the preceding type by being
longitudinally grooved and ridged. The cross-section is usually bicrescentic, two lateral wings rolling up dorsal-wards. This type of
pellet comprises several varieties : in Musculus marmoratus, the ribbons
have accessory lateral grooves on either side of the mid-ventral one
ICOHMAN Y. ARAICAWA
IIA. ROD-RIBBON
Pellet-type 9. Rod with a trefoil-shaped section
The pellets belonging to this type consist of a rod which is trilobed
in section. Of the three longitudinal ridges, the median one is fine in
texture with the surface occasionally broken by transverse clefts, while
the other two have a smooth but rather coarse surface. The depth and
position of the exterior grooves vary according to species. This type of
pellet is peculiar to species of Chlamys in the Pectinidae (Gastrotetartika).
Pellet-type 9a. Rod with a triangular section
Moore (1931a) examined pellet-type 9a in Chlamys triradiata
(Muller) (erroneously described as Pecten septemradiatus) and noted that
this type of pellet consists of a triangular-sectioned rod with rounded
margins, one being sharper than the other two, and with slightly concave sides.
111. RIBBON
Ribbon-like pellets are probably defecated by all of the Gastrotriteia and some of the Gastrotetartika, and can be classed under two
distinct types according to whether or not they are grooved. On the
whole, ribbon-like pellets are morphologically unstable, because the
form of the post-intestinal lumen tends to be affected by the dietetic
or physiological conditions of the animal.
Pellet-type 10. Ungrooved ribbon
This type of faecal ribbon is normally slightly curved and crescentic
in section and may be produced by a wide major intestinal typhlosole.
Pellet-type 10 probably occurs in nearly all of the Gastrotriteia and
some of Gastrotetartika, namely Arcidae, Pteriidae, Glycymeridae,
Pinnidae, Plicatulidae, Unionidae, Carditidae, Anomiidae and ZSpondylidae.
Pellet-type 10a. Grooved ribbon
This type of pellet possibly occurs in four families of the Gastrotriteia, namely Mytilidae, Ostreidae, Isognomonidae and some of the
Pectinidae. It can be distinguished from the preceding type by being
longitudinally grooved and ridged. The cross-section is usually bicrescentic, two lateral wings rolling up dorsal-wards. This type of
pellet comprises several varieties : in Musculus marmoratus, the ribbons
have accessory lateral grooves on either side of the mid-ventral one