Again, there lingers in the Cam, and a few other rivers of north-eastern Europe, that curious fish the eel-pout or ‘burbot’ (_Molva lota_). Now he is utterly distinct from any other fresh-water fish of Europe. His nearest ally is the ling (_Molva vulgaris_); a deep-sea fish, even as his ancestors have been. Originally a deep-sea form, he has found his way up the rivers, even to Cambridge, and there remains. The rivers by which he came up, the land through which he passed, ages and ages since, have been all swept away; and he has never found his way back to his native salt-water, but lives on in a strange land, degraded in form, dwindling in numbers, and now fast dying out. The explanation may be strange: but it is the only one which I can offer to explain the fact—which is itself much more strange—of the burbot being found in the Fen rivers. Another proof may be found in the presence of the edible frog of the Continent at Foulmire, on the edge of the Cambridge Fans. It is a moot point still with some, whether he was not put there by man. It is a still stronger argument against his being indigenous, that he is never mentioned as an article of food by the mediæval monks, who would have known—Frenchmen, Italians, Germans, as many of them were—that he is as dainty as ever was a spring chicken. But if he be indigenous, his presence proves that once he could either hop across the Straits of Dover, or swim across the German Ocean. But there can be no doubt of the next proof—the presence in the Fens (where he is now probably extinct) and in certain spots in East Anglia, which I shall take care not to mention, of that exquisite little bird the ‘Bearded Tit’ (_Calamophilus biarmicus_). Tit he is none; rather, it is said, a finch, but connected with no other English bird. His central home is in the marshes of Russia and Prussia; his food the mollusks which swarm among the reed-beds where he builds; and feeding on those from reed-bed to reed bed, all across what was once the German Ocean, has come the beautiful little bird with long tail, orange tawny plumage, and black moustache, which might have been seen forty years ago in hundreds on ever reed-rond of the Fen.