30 
J. R. RICHARDSON 
loop pattern therefore does not define the family 
position of Magas which may prove to be a 
member of the Dallinidae 
Discussion of the evolutionary derivation of 
members of the Anakineticinae will be included 
in a forthcoming paper on Australian Terebra- 
tellidae. 
The material described herein is housed in the 
collections of the South Australian Museum 
(SAM), the Western Australian Museum 
(WAM), and the Museum of Victoria (NMV). 
SYSTEMATICS 
Superfamily Terebratellacea King, 1850 
Family Terebratellidae King, 1850 
Subfamily Anakineticinae nov. 
Diagnosis. Posteriorly thickened smooth Tere¬ 
bratellidae with permesothyrid foramen; cardi- 
nalia consisting of socket ridges, crural bases, 
and a cardinal process with trefoil posterior sur¬ 
face. 
Genera included . Anakinetica Richardson, 1987; 
Adnaiida nov.; Aliquantula nov.; Australiarcula 
Elliott, 1959; Elderra nov.; Magadina Thomson, 
1915; Magadinella Thomson, 1915: Parakine- 
tica Richardson, 1987; Pilkena nov.; Pirothyris 
Thomson, 1927; Rhizothyris Thomson, 1915. 
Distribution. Cretaceous-Recent; Australia, 
New Zealand. 
Comments . All anakineticinid genera are pos¬ 
teriorly thickened with a permesothyrid fora¬ 
men. They differ from one another primarily in 
the cardinalia: in the extent of thickening of the 
hinge platform, in the presence of hinge pits or of 
a hinge trough and, if the latter is present, in its 
extent. 
Differential thickening is a reliable indicator 
of free life in living forms and a permesothyrid 
foramen of an inert, non-muscular pedicle 
(Richardson 1981a); i.e. individuals that are 
pediculate but are neither tethered nor fixed to 
the underlying substrate. The presence of a hinge 
trough or of pits is associated with different 
actions of the pedicle (Richardson 1987). In the 
former, the action of pedicle muscles rotates the 
pedicle or the shell (depending on the mass of 
substrate bonded with the pedicle); in the latter 
they push the pedicle in and out of its housing, 
the beak. Rotatory action is associated with a 
bonded pedicle and attachment of the dorsal 
pedicle muscles to a hinge trough. In/out action 
is associated with a free pedicle and attachment 
of dorsal adjustor muscles to a pair of posterior 
hinge pits. 
A hinge trough is characteristic of four of the 
genera and may (1) extend the full length of the 
platform {Magadina), (2) be restricted to its an¬ 
terior section as a result of enlargement of the 
inner socket ridges and cardinal process (Maga* 
dinella , Elderra ), or (3) be restricted to its pos- 
terior region {Aliquantula) by enlargement of the 
crural bases. Genera with hinge pits may differ 
in the position of the hinge platform relative to 
the valve surface and in shell shape and beak 
form, differences which, in members of living 
genera {Anakinetica, Parakinetica ), are related 
to direction of movement and to the disposition 
of the pedicle processes. 
Neither hinge trough nor pits are evident on 
the hinge platform of species of Adnaiida.fk 
absence of any area for attachment of the dorsal 
pedicle adjustor muscles is a likely indicator of 
atrophy or loss of the pedicle system, as are the 
small foramen and incurved beak also seen in 
these species. They would have been free-lying 
forms without any capacity to move and similar 
to some of the populations of Neothyris lentica- 
laris described by Chapman & Richardson 
(1981) and Richardson (1981b). Species within 
each genus are distinguished on consistent dif¬ 
ferences in size and shape, on loop pattern, and 
on details of the hinge platform. Loop pattern is 
linked with the space available within the 
mantle cavity. In shells of small size and heavy 
thickening {Magadina, Anakinetica recta) the 
adult loop is at an early stage in the develop¬ 
mental sequence; i.e. with a ventral ring and 
wide descending branches separately attached to 
a high median septum. A long reflected loop 
without septal attachments is found in Aliquan- 
tula and Elderra , genera of moderate size and 
having the hinge platform smaller in relation to 
val ve area than i n Anakinetica and Magadinella . 
The loop is rarely recovered in its entirety but its 
parts and their relationship are evident during 
dissection. 
Several Japanese species are difficult to dis¬ 
tinguish from Australian anakineticinids. The 
Miocene species Tanakura tanakura Hatai, 
1936, for example, was included by me 
(Richardson 1987) in the Magadinae because of 
its similarity to species of Anakinetica. ThePlio- 
cene-Recent species Nipponithyris nipponemis 
Yabe & Hatai, 1934 is also very similar to 
Aliquantula insolita. However, the adult loop of 
N. nipponensis displays double lateral connect¬ 
ing bands (Richardson 1975), showing that it isa 
member of the Dallinidae. The development 
