360 Evolution and Distribution of Fishes 



correct from the fact, which may account for the distribu- 

 tion of the whole genus, that it is not confined to fresh- 

 waters, but occurs also in the sea "(2: 607)." 



Though the above conclusion is strongly urged by so 

 eminent as authority as Boulenger (252:84) the writer 

 would venture to give a different explanation, and one that 

 will apply equally to the Haplochitonidae. It is that these 

 represent southern stranded outliers of ancient teleosts, 

 which inhabited, in continuous relation, areas of an extreme 

 southern continent, before final breaking up of that land 

 mass took place. For one may well ask why it was that 

 the same species or genus of marine fish took to rivers of 

 three continents, as well as the outlying New Zealand 

 islands, without leaving a better remnant than one marine 

 species now. Again they possess an air-bladder as a ganoid 

 heritage. So the sole marine species of the Chatham 

 Islands could appropriately be viewed as a marine deriv- 

 ative from an evidently ancient freshwater stock; while 

 Neochanna retains its old environment in New Zealand. 



The same line of reasoning would apply to Haplochiton 

 that is alone found in freshwaters of Patagonia, Chile and 

 the Falkland Islands; and to Prototroctes, that is repre- 

 sented by one species each in New Zealand, Queensland, 

 and S. Australia. But the entire question raises issues of 

 so wide a kind that the writer devotes a subsequent chapter 

 (Ch. 15) to its discussion. 



In seeking however for the earliest known types of the 

 Haplomi (Esociformes) one is carried back to Upper 

 Cretaceous times, and largely to what seem truly marine 

 strata. For the families Enchodontidae, Scopelidae, Chiro- 

 thricidae, and others are well represented in strata of those 

 times. Greatly as already described for Clupeidae, it can 

 be suggested that the primitive types of Haplomi developed 

 first in the early Cretaceous period or possibly in the late 

 Jurassic period. Next, between that period and late Cre- 

 taceous days, a splitting ecologically of the group seems to 

 have taken place. This resulted, during the later Cretace- 

 ous and early Tertiary period, in development of such 

 families as the Esocidae, Dalliidae, Kneriidae, Cyprinodon- 

 tidae, Amblyopsidae, and Percopsidae that remained in 



