BRITISH AVONIAN CONODONT FAUNAS 207 
Zone 
375 
i SS —— re | eet 
"ie Pseudopolygnathus Pseudopolygnathus 
multistriatus Pseudopolygnathus multistriatus 
Zz multistriatus 
300 
Spathognathodus Sani! eS —S 
costatus 
sensu ER. Branson 
Reece pebenathes aie Pseudopolygnathus 
til Juveni 
Boo! GST ee: Pseudopolygnathus erat 
Pseudopolygnathus dentilineatus 
dentilineatus- 
100 
K 
25 
- 2 Pseudopolygnathus 
: vogesi. 
ToVl 
Spathognathodus 
spinulicostatus 
sensu Ziegler 
Spathognathodus 
costatus 
sensu Ziegler 
Spathognathodus 
aculeatus 
Fic. 43. Phylogeny of the genus Pseudopolygnathus and related forms in the Avonian. 
Vertical lines : stratigraphic range. Full arrows: phylogenetic development. Half 
arrows : morphological variation at one horizon. 
