THE STATE GEOLOGIST. 55 



tinopterygian), from which the manifold variety of modern 

 bony fishes has been derived. Both of these orders are repre- 

 sented in the Devonian, but the former greatly predominate, and 

 the latter only begin to outstrip them during the Carboniferous. 

 There is but little reason to doubt that the fringe-finned Ganoids 

 gave rise to the class of amphibians, which makes its first appear- 

 ance in the Carboniferous, this class in turn being ancestral to 

 reptiles, and the latter to birds and mammals. The history of 

 Crossopterygians is strikingly similar to that of Dipnoans, in that 

 the majority of forms become extinct before the close of the Meso- 

 zoic, although in each case a few moribund survivors continue on 

 to the present day. Only a solitary member of the order occurs in 

 the Xewark series of this State, a large form known as Diplurus, 

 of which not more than three or four examples have come to light. 

 A more particular notice of this form will be found in a subse- 

 quent section of this report. 



Our attention may now be claimed by the important order of 

 Acanthopterygii, which embraces not only large numbers of enam- 

 eled-scale fishes, but all modern Teleosts, or so-called "bony 

 fishes." The earliest and most primitive member of this order 

 is Cheirolepis, which occurs in the Devonian of North Britain and 

 Canada; but this is succeeded in the Carboniferous and Permian 

 by a variety of forms, all exhibiting the same general features, and 

 commonly grouped in the single family Palaeoniscidae. There is a 

 marked resemblance between the members of this family and 

 modern sturgeons and paddle-fishes ; these latter, accordingly, can 

 hardly be looked upon other than as late survivors of the ancient 

 stem. Their similarity of structure is most evident in the struc- 

 ture of their fins, especially the heterocercal tail, and in the pres- 

 ence of characteristic plates (the so-called infraclavicles) in the 

 jugular region. As for the degeneration of teeth and scales in 

 recent forms, these seem to be characters of minor importance. 

 Hence we may say that primitive sturgeons arose in the Devon- 

 ian, and after giving off more specialized branches during the 

 Palaeozoic and Mesozoic, maintained a conservative existence 

 down to the present day. Consequently, the longevity of the 

 sturgeon tribe is no less remarkable than that of Lung-fishes, 

 fringe-finned ganoids, and cartilaginous fishes like the Port Jack- 

 son shark. 



