BUFFALO SOCIETY OF NATURAL SCIENCES 1 85 



Devonic fishes of North America here referred to have been shown, 

 from their occurrence and distribution, to be mostly if not entirely 

 fluviatile (Grabau 87, 88). 



Macnair and Reid have with great justification brought forward 

 many objections to the "Lake theory" advocated by Geikie, but their 

 logic fails them when they contend that because the Old Red fish 

 and eurypterids could not have been lacustrine forms, therefore they 

 must have been marine. 



The river origin seems never to have occurred to these two writers, 

 or else if it did they considered that the same objections were open 

 to it as to the lake origin. One of the arguments which they advance 

 against the lake theory is the difficulty of the origin and distribution 

 of the fish and eurypterids. They argue thus: these forms were pres- 

 ent in the Siluric and so it is not strange that they should occur also 

 in the Devonic; "but of the genera Osteolepis, Dipteris, Glyptolepis, 

 and other fishes of the Old Red Sandstone no undoubted plates or 

 scales occur in the preceding formation. The question therefore 

 arises, whence came these highly organized fishes of the Old Red 

 Sandstone? More especially, from what fresh-water region did they 

 migrate? Not only so, but as the same genera of fishes occur in the 

 Devonian of North America and the St. Lawrence basin, we have 

 an equal right to know by what fresh-water pathway of distribution 

 they were enabled to migrate some 3000 miles between one point and 

 another" (160, 218, 219). But surely such facts of distribution should 

 not be distressing; many a case could be cited in the recent fresh- 

 water fish fauna of the same genera occurring more than 3000 miles 

 apart, and with perhaps no related genera in the intervening area. 

 One may mention the case of the genus Umbra, a form so peculiar 

 as to be made the type of a family in which are only two species, 

 these being most closely allied, and yet one occurs in the rivers of the 

 Atlantic states of North America and the other in the Danube system, 

 some thousands of miles distant. Even more remarkable is the genus 

 Scaphirhynchus among the sturgeons, which likewise has two species: 

 one in the Mississippi system, the other in Central Asia. In the same 

 family is the genus Polyodon, with two species only, one in the Missis- 

 sippi, the other in the Yangtse-kiang. But one need not confine the 

 illustrations to genera which are identical in distant regions; species offer 

 even more surprising examples. Perca fluviatilis,Gastrosteus pungitius, 

 Lota vulgaris, Salmo solar, and many others might be mentioned, in- 

 habiting both the rivers of eastern North America and of Europe. For 



