FISHES. 53 



they run north-eastwards to the Orkney Islands, where they 

 are found in June, divide at the British Isles about August, and 

 again unite to run towards the south-west in October and 

 November, whilst in December they are found at some distance 

 from the west coast of America, in about 18 or 20 N. L. Then 

 they return northwards to Georgia, &C. 1 These results, indeed, 

 are founded upon the supposition that the herring of the east 

 coast of North America belongs to the same species with that 

 of the North Sea, which, however, has been since found not to 

 be the case 2 . On the whole there still prevails much uncertainty 

 respecting the migration of fishes. Most of them do not migrate, 

 or their expeditions are rather to be compared with those of birds 

 of passage, which, without any determinate course, betake them- 

 selves now and then from one place to another. Those marine 

 fishes, which may really be named fishes of passage, change in the 

 northern hemisphere the northern for more southern regions in the 

 spring of the year, whilst birds of passage do the same in the 

 autumn. The cause, therefore, of the passage of fishes must be 

 different from that of birds 3 . 



Some species of fishes can exist for a longer or shorter period on 

 dry land, as the common eels. Different species of Callichthys and 

 Doras bury themselves in the mud when the ponds in which they 

 live become dry, or even creep, as HANCOCK witnessed in a species 

 of Doras, over the ground, sometimes in large troops to another 

 pond. The sand-eel (Ammodotes tobianus) lives in the sand and 

 especially in the clayey bottom of the sea, in which it buries 

 itself deep and through which it winds in all directions ; it some- 

 times approaches so close to the shore that it may be dug out at 



1 Observations on the annual Passage of Herrings, Transact, of the Americ. Philos. 

 Soc. Vol. II. Philadelphia, 1786, pp. 236 239. 



2 The herring of New York is Clupea elongata LESUEUB. See Cuv. et VAL., Hist, 

 not. des Poiss. XX. p. 247. ["There can be no doubt that the herring inhabits deep 

 water all round our coast, and only approaches the shores for the purpose of depositing 

 its spawn." YARRELL British Fishes, u. p. 112; see the paper of M c CuLLOCH quoted 

 by YARRELL in Journ. of Roy. Institution, Jan. 1824.] 



3 A prize essay of MARCEL DE SERRES on the History of Fishes of Passage (NatuurL 

 Verhandelingen van de Holl. Maatschappij der Wetenschappen te Haarlem, lie Verzam. 

 IQ Deel. 1842, 4to) throws little light on this matter, and may be regarded as a failure. 



