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 assigned to a species, and to a genus only with great caution. LITERATURE CITED ALDINGER, H. 1931. Ueber karbonische Fische aus Westfaelen. Paleont. Zeit., 13:186-201. BERG, L. S. 1940. Classification of fishes, both Recent and fossil. Moscow and Leningrad, 1940 (J. W. Edwards, Ann Arbor, Michigan, 1947, offset reproduction, pp. 1-345, 197 figs., plus English translation of text, pp. 346-517, 1947.) FIEGE, K. 1951. Eine Fisch-Schwimmspur aus dem Culm bei Waldeck. Neues Jahrb. Geol. and Palaeont. Jahrgang 1951:9-31. HIBBARD, C. W. 1933. Two new species of _Coelacanthus_ from the middle Pennsylvanian of Anderson County, Kansas. Kansas Univ. Sci. Bull., 21:279-287. KELLER, G. 1934. Fischreste aus dem oberkarbon des Ruhrgebiets. Gluckauf, 70:913-917. MOORE, R. C., ELIAS, M. K., and NEWELL, N. D. 1936. A "Permian" flora from the Pennsylvanian rocks of Kansas. Jour. Geol., 44:1-31. MOY-THOMAS, J. A. 1935. A synopsis of the coelacanth fishes of the Yorkshire Coal Measures. Ann. Mag. Nat. Hist., 15 (ser. 10): 37-46. 1937. The Carboniferous coelacanth fishes of Great Britain and Ireland. Proc. Zool. Soc. London, 107 (B): 383-415.