320 Evolution and Distribution of Fishes 



or spines, amid Carboniferous Limestone deposits, the 

 freshwater Elasmobranchs, Dipneusteans, and Crossoptery- 

 gians, were spreading alongside Chondrosteans. There- 

 fore such a freshwater bed as Traquair calls (77:4) the 

 "Gilmerton ironstone" is spoken of thus: "between the 

 lowest marine limestones is a well-known coal seam the 

 North Greens, and not far above is the Gilmerton Iron- 

 stone" which yielded: 



Acanthodes sp. Eiirynotus crenatus 



Gonatodus macrolepis Megalichthys sp. 



Elonichthys robisoni Rhizodus hibbert't 



Elonichthys multistriatus Rhizodus ornatus 



Nematoptychiiis greenocki Sagenodus quinquecostatus 



also the labyrinthodonts Pholidogaster pisciformh, Loxo- 

 mma allmani, d.ndMacro7?ierium scoticiim. His succeeding 

 observation then is wide of the mark: "Here it will be seen 

 that the elasmobranch fauna of the marine limestone is 

 utterly wanting, and the estuarine fishes have returned." 

 The writer would incline to phrase it thus : "After depo- 

 sition of the lower marine limestone bed, marked elevation 

 of the land occurred. Over this an abundant marshy vege- 

 tation developed, that originated the "North Greens" coal, 

 while still later part of its surface became a lake that soon 

 was invaded by freshwater fishes and giant amphibians 

 whose remains are left in the freshwater ferruginous rock- 

 deposits." 



From the above also it will be seen that the statement 

 of Sauvage for the Lower Carboniferous (Calciferous) 

 of Scotland is incorrect when he says: "Tandis que les 

 Ganoides en general, et les Palaeoniscides en particulier, 

 sont singularement rares dans le Carbonifere inferieur, nous 

 devons noter leur abondance a Eskdale et a Liddesdale." 

 The Palaeoniscidae were often extremely abundant and 

 were widespread by the close of the period, as were also 

 the Platysomidae treated of below. 



During Mid-Carboniferous and Coal Measure times, 

 some of the above "Calciferous" genera persisted, while 

 Elonichthys, Cryphiolepis^ and Acrolepis continued even 

 into the Permian, but wholly in freshwater environment. 

 The distribution of the species of Acrolepis moreover from 



