NO. l8.] TRIASSIC FISHES OF CONNECTICUT. 20. 



14. Semionotus robustus (Newberry). 



15. ^Semionotus tenuiceps (Agassiz). 



Family Eugnathhle. 



16. *Ptycholepis marshi Newberry. 



On comparing the foregoing lists, it appears that both faunas 

 — the Lombardy and the eastern North American — are made 

 up exclusively of ganoids ; and of these a single Crossopterygian 

 family is represented in each case, while the remainder belong 

 to the Actinopterygian order. Sharks and rays, Chimseroids 

 and Lung-fishes, are conspicuously absent from both regions. 

 Of the two families common to both provinces, of which Semiono- 

 tus and Catopterus are representatives, the former is in each case 

 the most important in point of numerical abundance, and is repre- 

 sented by the largest number of species. Dictyopyge is not 

 common to both regions, nor conclusive as to age, since it ranges 

 from the Bunter to the Upper Keuper in the Anglo-German 

 Trias, and is known also from the Karoo formation of British 

 South Africa and the Upper Trias of New South Wales. Two of 

 the remaining genera of the American Trias are exceedingly 

 rare in the Occidental region, each being represented by a solitary 

 species. These are Acentrophorus and Ptycholepis. Of the 

 former it is to be observed that it is apparently capable, despite 

 its imperfect preservation, of being included in the same family 

 as Semionotus; and as for the latter, of which only a few examples 

 have been found at a single locality, near Durham, Connecticut, 

 it is significant to note its occurrence at a slightly higher horizon 

 in the Alpine Keuper (Besano and Raibl), where it is likewise 

 accompanied by members of the Semionotidse. 



From the facts that have just been set forth one may infer 

 that the so-called " Newark " fish fauna of this country is of 

 more or less composite character, in that its chief constituents, 

 or their analogues at least, are distributed between the middle 

 (Ladinian) and upper (Keuper) divisions of the Alpine Trias. 

 That a general correspondence exists between the Atlantic border 

 fish fauna and that of the Middle Trias of Lombardy is now 

 sufficiently evident ; such relations as can be predicated between 

 the former and various Keuper fish faunas of the Mediterranean 



