310
IiOHMAN Y , ARAIiAWA
on the histological preparations of sections mounted by the usual techniques ; after fixation in Bouin’s solution, 10 p sections were cut and
stained with Delafield’s haematoxylin and eosin.
Listed in Table I1 (p. 370) are the scientific name, pellet-type, size
and locality of the animals from which the faecal pellets have been
collect,ed.
111. MORPHOLOGY
A. ClassiJication of faecal pellets
The faecal pellets in the Bivalvia can be divided into various types
according to structure and form (see Figs. 1 and 2), and attempts at
classification have been made by several workers. The first attempt was
made by Moore (1931) who roughly divided them into four types,
(1) oval pellets, (2) ribbon pellets, (3) triangular and trefoil section rods,
and (4) coiled rods. Moore and Kruse (1956) amended this as follows :
(1) ovoid or ellipsoid, (2) ellipsoid to rod-like, (3) rod with external longitudinal sculpture, (4) rod with longitudinal and transverse sculpture, and
( 5 ) ribbon-like. A more systematic attempt was made by Arakawa
(1962) who divided the faecal pellets into three large categories, oval,
rod and ribbon, and then subdivided them under the fourteen types
according to shape, subovoid, segmental, rosarioid, orthocylindric, trigonal, spiral, pentafoliate, septemfoliate, multifoliate, trifoliate, bicrescentic, chevron-shaped, plano-concave and bi-cricoid. The number of
observed types of pellets has increased remarkably since then, and not
all fit within the previous schemes of classification. A thoroughly revised classification and a definition of pellet-types within the Bivalvia
are therefore provided, covering over one hundred and sixty-four representatives of forty-five families in five orders concerned. These are
summarized in Table I.
B. DeJinition of pellet-typps
I. OVAL
The following four pellet-types included under this class commonly
occur in Gastropempta (classification of Purchon, 1963). Each of these
types is distinguishable from the other according to shape, sculpture
and ratio of length to breadth of pellets.
Pellet-type 1. Ovoid
This type of pellet is possibly produced by seven families in the
Gastropempta, namely the Tellinidae (Fabulina, Semelangulus, Psam-
IiOHMAN Y , ARAIiAWA
on the histological preparations of sections mounted by the usual techniques ; after fixation in Bouin’s solution, 10 p sections were cut and
stained with Delafield’s haematoxylin and eosin.
Listed in Table I1 (p. 370) are the scientific name, pellet-type, size
and locality of the animals from which the faecal pellets have been
collect,ed.
111. MORPHOLOGY
A. ClassiJication of faecal pellets
The faecal pellets in the Bivalvia can be divided into various types
according to structure and form (see Figs. 1 and 2), and attempts at
classification have been made by several workers. The first attempt was
made by Moore (1931) who roughly divided them into four types,
(1) oval pellets, (2) ribbon pellets, (3) triangular and trefoil section rods,
and (4) coiled rods. Moore and Kruse (1956) amended this as follows :
(1) ovoid or ellipsoid, (2) ellipsoid to rod-like, (3) rod with external longitudinal sculpture, (4) rod with longitudinal and transverse sculpture, and
( 5 ) ribbon-like. A more systematic attempt was made by Arakawa
(1962) who divided the faecal pellets into three large categories, oval,
rod and ribbon, and then subdivided them under the fourteen types
according to shape, subovoid, segmental, rosarioid, orthocylindric, trigonal, spiral, pentafoliate, septemfoliate, multifoliate, trifoliate, bicrescentic, chevron-shaped, plano-concave and bi-cricoid. The number of
observed types of pellets has increased remarkably since then, and not
all fit within the previous schemes of classification. A thoroughly revised classification and a definition of pellet-types within the Bivalvia
are therefore provided, covering over one hundred and sixty-four representatives of forty-five families in five orders concerned. These are
summarized in Table I.
B. DeJinition of pellet-typps
I. OVAL
The following four pellet-types included under this class commonly
occur in Gastropempta (classification of Purchon, 1963). Each of these
types is distinguishable from the other according to shape, sculpture
and ratio of length to breadth of pellets.
Pellet-type 1. Ovoid
This type of pellet is possibly produced by seven families in the
Gastropempta, namely the Tellinidae (Fabulina, Semelangulus, Psam-