i6o Evolution and Distribution of Fishes 



structlve is the association at Cannelton, though the vege- 

 tation is more fragmentary." 



The rich eastern Australian oil shales that have been 

 described by Carne {112) and others, also the associated 

 beds of calcareous and arenaceous shale, have yielded as 

 yet few traces of fishes. Suessmilch, however, notes (US'- 

 138) that: "a fossil fish (Urosthenes aiistralis) has been 

 obtained from the Upper Coal Measures, both in the 

 Lithgow and Newcastle districts, while from the latter 

 locality the wings of some undescribed insects, belonging 

 probably to the Neuroptera, have been obtained." A 

 labyrinthodont and abundant fossilized plants alongside 

 caused him to regard all as of freshwater origin. 



The remarkable set of fish remains that has been de- 

 scribed by A. S. Woodward {114:1) from calcareous, 

 arenaceous, and shale beds of Mansfield in Victoria, prob- 

 ably belong to the same rock series as that which fur- 

 nished Urosthenes further north. They indicate a Car- 

 boniferous age, and are preserved alongside abundant plant 

 remains in some strata, though without trace of marine 

 organisms. The most striking and probably most abundant 

 type of fish is that named Gyracanthides murrayi by Wood- 

 ward (Fig. 19). Belonging to the primitive elasmo- 

 branchs, it first clearly revealed the exact disposition of 

 the formidable fin-spines that have been named Gyr acanthus, 

 and which occur at times in considerable amount in Car- 

 boniferous and Carbo-Permian beds from central North 

 America to Britain. In addition to remains of acan- 

 thodian elasmobranchs, the other fishes belong to Ctenodus, 

 a genus of ancient Dipnoans; and to Elonichthys and Strep- 

 sodtis among ganoids. All of this is added proof that 

 from northern Europe and America to Southern Australia, 

 freshwater passageways existed that permitted steady mi- 

 gration and variation amongst related groups of fishes. 



We may shortly sum up now, for the fishes of the Coal 

 Measures, by saying that the once prevalent and primitive 

 Ostracoderms and Arthrodires had wholly disappeared; 

 the primitive and rapidly evolving Elasmobranchs were the 

 most predaceous and lithe. So some of the latter gradually 



