ORDOVICIAN BIVALVE BIOGEOGRAPHY 37Fig. 2. Continental reconstructions for the Ordovician. (a) Early Ordovician. Note near-polar position of the
Montagne Noire and the lower-latitude position of Avalonia which is still on the Gondwanan margin. Contrast
with the lower latitudes of Argentina and Australia, (b) Mid-Ordovieian. Note lower-latitude position of
Avalonia, whilst Armorica stays at polar latitudes, (c) Late Ordovician. Note positions of Baltica and
Laurentia, both areas of carbonate platforms.
Key to abbreviations: Ar, Arrnorica; Av, Avalonia; B, Baltica; Bh, Bohemia; G, Gondwana; K, Kazakhstania;
La, Laurentia; S, Siberia; SC, South China; U, East Uralia. Reconstructions principally based on those of
Torsvik (1998) with modifications by L. E. Popov.
Deceptrix by Pojeta (1978 p1. 2, figs 1-2), but
Cope (1997b) showed that the latter genus was a
cardiolariid and not a praenueulid (see below).
Some of the species figured previously as
Deceptrix, in addition to some of those figured
by Pojeta (1971, 1978), including those figured
by Tunnicliff (1982) and Cope (1996a), are
now recognized as praenuculids and not
cardiolariids. For those species Cope (1997b)
proposed the praenueulid genus Homilodonta
with Arca subtruncata Portlock, 1843 as type
species; a full description and designation of a
lectotype of this species was made by Tunnicliff
(1982, pp. 60-61, p1. 9, figs 1-7, 9-11)