XL— NOTES ON TRTASSIC FISHES BELONGING TO THE 

 FAMILIES CATOPTERID.^ AND SEMIONOTID/E. 



By C. R. Eastman. 

 (Plates XXX-XXXII). 



Highly characteristic of the early Mesozoic in this and other countries 

 is the short-lived family of "ganoid" fishes known as the Catopteridae, 

 a group descended in all probability from primitive Palaeoniscid 

 stock, comprising only three genera, so far as known, attaining a wide 

 distribution in nearly all continents, and becoming extinct at the close 

 of Triassic time. 



The type-species of the genus Catopterus, C. gracilis, was described 

 by J. H. Redfield in 1837. A decade later the second known species 

 of Catopterus was described by Sir Philip Grey Egerton, and at the 

 same time the new genus Dictyopyge was established by him upon the 

 evidence of certain well-preserved fishes obtained between 1840 and 

 1845 from the Richmond coal-field of Virginia. 



More widely distributed than Redfield's genus, which is limited 

 to eastern North America, Dictyopyge differs from Catopterus only in 

 the more forward position of the dorsal fin, which never arises behind 

 the origin of the anal. Dictyopyge macrura, the type, first described 

 by W. C. Redfield, under the name of Catopterus macrurus, is re- 

 stricted to the Trias of Virginia and the Connecticut Valley. A 

 number of other species are known, however, from the Upper Trias 

 of England, Ireland, Germany, Switzerland, and New South Wales, 

 and from the Upper Karoo formation (Stromberg beds) of the Orange 

 Free State in South Africa. 



The third known member of the family under consideration is the 

 genus Perleidus. The type and only known species, P. altolepis 

 (Deecke), occurs in the Alpine Middle Trias of Perledo, Lombardy, 

 where it is accompanied by representatives of the families Coelacan- 

 thidse and Semionotida?, not unlike those occurring in the Trias of 

 eastern North America. In general proportions of body, position of 

 median fins, squamation, and arrangement of facial plates, Perleidus 

 approximates Catopterus more nearly than Dictyopyge. A certain 



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