The Chondrostei and Holostei 329 



In the American beds Diplurus, Catopterus, and Dicty- 

 opyge — already (p. 324) reviewed — lived side by side with 

 Acefitrophorus (v.s.), with ten species of Semionotus, and 

 with Ptycholepis noted below {228). From the Raibl 

 beds that we have shown to be freshwater, (Chap. 10, p. 

 312) not marine, Dapedius and Colobodus are alongside 

 four species of Belonorhynchus, five of Pholidophorus, 

 (vide infra) and Ptycholepis. Many quotations could be 

 given also which abundantly prove that all of the species 

 of Semionotidae were of freshwater habitat, of great abund- 

 ance, and of wide distribution. 



But when, as in the case of the Perledo beds of N. Italy, 

 Bassani and predecessors describe fishes, reptiles, and even 

 plant remains in the same paper that has descriptions of 

 ammonites and other typically marine "moUuschi," one is 

 apt to conclude that all were marine unless some very clear 

 distinction is made. Such distinction, however, is often 

 not emphasized. But in Bassani's paper (pp. 58-59) he 

 notes, on the faith of Barazzetti, that the plants, fishes and 

 reptiles, also a very imperfect and doubtful crustacean, were 

 all found in an upper zone about M. 5.50 thick; while the 

 ammonites and other molluscs were only found in a bed 

 below of about M 0.50 thickness. And he puts this infor- 

 mation in graphic form thus: 



M 5.50 



M 0.50 



Pianti-Pesci 

 Rettili-Crustacei 



Molluschi 



So, as in the Upper Trias of Connecticut, we have here 

 a like association of plants, fishes, and reptiles of fresh- 

 water habitat, and all embedded in a clay that was deposited 

 in some rather extensive lake. This lake also may have run 

 nearly parallel to, and at no great distance from, a sea 

 shore. But this lake had resulted after elevation of a sea 

 floor, which while submerged received marine deposits 

 that covered over and preserved molluscs which had lived 

 there. 



