404
KOHMAN Y . ARAKAWA
are there marked scatological differences between genera and species
(Tables I11 and IV). Apart from the Limopsidae and the Spondylidae,
there is remarkable uniformity of pellets within the order Gastrotriteia.
TABLE IV. SIMILARITIES OF PELLET-TYPES AMONG VARIOUS
TAXONOMIC DIVISIONS
Order level
Familial level
(Pellet-type)
(Pellet-type)
GASTROTRITEIA (PROTOBRANCHIA)
(111-10, 10a)
Nuculanidae (11-6)
(except for
(SEPTIBRANCHIA)
Spondylidae and
Limopsidae)
(GASTROTRITEIA)
Cuspidaridae ( 1 1 )
Arcidae (111-10)
Glycymeridae (111- 10)
Limopsidae (11-4)
Mytilidas (111- 1 Oa)
Isognomonidae (111- 10a)
Pinnidae (111-10, l O a )
Ostreidae (111-lOa)
Spondylidae (11-4, ?III-10)
(GASTROTETARTIKA)
Limidae (?II-Sa)
Unionidae (111- 1 O?)
Chamidae (11-4)
Laternulidae (11-4)
(GASTROPEMPTA)
Corbulidae (11-4)
Veneridae (11-4, etc.)
Psammobiidae (1-1, 2)
Myidae (11-5)
Semelidae (1-1, la)
Solenidae (IA-3, 1-2)
Corbiculidae (11-4)
Cardiidae (IA-3, 1-1)
Generic and specific level
(Pellet-type)
-
-~
Nuculidae
Nucula hanleyi]
N. nucleus
N . turgida
N. rnoorei 7
N . tenuis
](II-7)
N . sulcata (11-7b)
Pecten (11-8)
Chtamys (IIA-9)
Delectopecten (111-lOa)
Phlyctaenachlamys
lysiosquillina ( 1 la)
Scintilla japonica (I- 1)
Tellina-form (1-1)
Macoma-form (I-la)
Mactra, Raeta (1-2)
Tresaus, Schizo -
thaerus (IA-3)
Pholadidea (11-5)
Barnea (I-la)
Zirjaea (11-4)
N. sp.
Pectinidae
Galeommidae
Tellinidae
Mactridae
Pholadidae
While it was recognized that no one characteristic feature of the
pellets would be a satisfactory index, yet taken in combination the
following features should be of major significance : (1) external sculpture
(cross-section) ; (2) size (length/breadth ratio) ; (3) colour ; (4) texture.
External sculpture
The external sculpture or markings are a reliable criterion for
the pellets of a number of species, e.g. in the Nuculacea and Pectinacea.