Dear Sir

The Common Pike and Salmon are the only fishes that I recollect at present which are common to the fresh-waters of Europe and North America.¹ The identity of the American Pike with the European one has been called in question but some American Ichthyologists, but I am convinced wrongly, because they had no specimen or no good specimen of the Common Pike of Rupert’s Land² to compare with— I most minutely examined the American Salmon & the Pike with European ones and feel assured that precisely the same species of each exists in both hemispheres— There are other pikes in Rupert’s land & Agassiz believes that there is a peculiar species in each river system— The Salmon also extends along the Labrador coast to the arctic sea north of America but I am not sure that it goes on to Behrings Straits— The numerous Salmon of the seas of Kamtschatka & Beerings Sea down to the Oregon seem to have much resemblance to the Asiatic ones described by Pallas but they have not been compared. Many of the Sclerognathæ are common to the English channel, the Baltic, the Greenland seas and american arctic seas but in Beerings sea where that family also abounds the forms are different from the European ones. The same genera of fish are common to the northern parts of the old & new worlds, with exceptions, but the species differ— The American Siluridæ are a totally distinct group from the Asiatic ones & in the temperate regions of Am^a there are many genera not found elsewhere, of all divisions of Fresh water fishes. The Salmon speaking roundly does not go south of the 40^th parallel and only a stray one enters the Mediterranean. One once appeared at the market in Malta—

Trout are natives of northern regions— D^r Hooker found them to the north of the Himalaya’s but not to the south— In Australasia & Patagonia, the Trouts are replaced by Galaxias, fish assuming the external appearance & beautiful spotting of the Trout but wanting the Adipose fin. There are many genera in the high southern latitudes which do not exist to the north of the equator. Certain species Muræna helena, Elecata and I believe some Scopelidæ or (Sauridæ as the family has been named) are also cosmopolite in the temperate & warmer seas Several sharks also—

Of sea fish there are certainly some forms common to the coasts of Australia & those of Japan but in the latter the curious northern Sclerogenidæ begin to appear & I should suppose that in the north of Japan and along the shores of Sagalien the general features of the ichthyology have changed. From the southern part of Japan down to the Indian Archipelago, westward to near the Cape of Good Hope southward to Australia and eastward to the China seas again the great mass of species is the same though there are some genera and species which are very local.

Many of the red sea genera and the fresh water fishes of the Nile are represented in the Senegal and on the Goldcoast but the species as far as I have learnt are never the same— Curious forms with lung-like air-bladders, exist on both sides of Africa but are not confined to that continent—

The Falkland Island fish resemble those of south New Zealand & islands further south but differ from the Japanese & northern forms— I do not think that any fresh-water species is common to the Falklands and New Zealand— Marine species are³ The Ichthylogy of the higher southern latitudes has a peculiar character from the predominance of certain forms. I believe that ranges of fresh water species to two continents will be found chiefly among anadromous fish. The Pike descends into salt water but I have not heard of its having been taken at sea. It is said to be found in Lake Aral. Sticklebacks which are very nearly alike on both continents, (the differences being as little as those which the species assumes in one locality,) are also inhabitants of the sea & one was taken by Sir Edward Belcher beyond Wellington inlet, which would have passed for an English one, if its origin had not been known.

I have answered your questions I think but have written hurriedly, being unable at present to devote much thought to the subject—⁴

Yours faithfully | John Richardson