er fishes,
and that many were from swamp deposits. If Keller is correct, then
members of the genus _Synaptotylus_ may have inhabited the lagoon, the
adjacent sea, or the streams draining into the lagoon. Perhaps these
fishes swam upstream, as modern salmon and tarpon do, although there is
no direct evidence for this. Possibly they lived in the lagoon at times
of scant rainfall and little runoff, when the salinity of lagoon water
approached normal marine values or the fishes may have lived in the
streams, and after death were washed into the lagoon. As numerous
remains of land plants and animals were washed in, perhaps this best
accounts for the presence of the fish in nearly all layers of the
deposits, not only the marine strata.

SUMMARY

A new genus of Pennsylvanian coelacanths, _Synaptotylus_, is described
and a previously named species, _Coelacanthus newelli_ Hibbard, 1933
(_C. arcuatus_ Hibbard, 1933, is a junior synonym), is referred to this
genus. All specimens of _Synaptotylus newelli_ (Hibbard) were collected
from the Rock Lake shale member of the Stanton formation, Lansing group,
Missouri series, six miles northwest of Garnett, Anderson County,
Kansas. _Synaptotylus_ is distinguished from all other coelacanths by a
basisphenoid having large, knoblike antotic processes each connected by
a low ridge to a small basipterygoid process. _Synaptotylus_ is most
closely related to _Rhabdoderma_, but is intermediate between
_Rhabdoderma_ and _Coelacanthus_ in shape of the fin girdles and basal
plates. Two new subfamilies, Diplocercinae and Rhabdodermatinae, of the
family Diplocercidae, are proposed. _Synaptotylus_ and _Rhabdoderma_ are
included in the subfamily Rhabdodermatinae, because both exhibit reduced
ossification in the endocranium and retain basipterygoid processes.

Loss of the basipterygoid processes in post-Carboniferous coelacanths
may reflect the development of a more efficient feeding mechanism, by
allowing the palatoquadrate complex and mandible to swing farther
laterally and expand the oral cavity.

_Synaptotylus newelli_ (Hibbard) may have occupied either the sea or
fresh water; these fishes occur in lagoonal deposits with reptiles and
amphibians, arthropods, marine invertebrates and remains of land plants.

Because scale patterns on _Synaptotylus_ and _Rhabdoderma_ are so nearly
similar and vary with size of the scale and its location on the fish, it
is recommended that isolated scales not be as