Hypothesis to Describe the Distribution of the Various Stages. 39 



already the embryos iu the eggs very far advanced in development, an indication 

 that it had probably been carried a considerable distance from its place of origin. 

 Similarly, the eggs in the sheet of spawn procured by Williamson outside Loch 

 Bracadale, Skj^e, contained well-developed embryos. 



On the American side of the Atlantic, the shallow water area is of limited extent, 

 and the deeper waters of the continental shelf are in close proximity to the coast, 

 and it is not strange, therefore, that American workers should have been the first 

 to describe the floating sheets of spawn of the Angler. It is so common on the 

 western side that the fishermen have given it the popular name of the " piirple 

 veil." In the descriptions of the floating spawn given by Agassiz and Whitman, 

 there is no e\ddence, however, that they ever found eggs which had been recently 

 spawned. Indeed, as has already been pointed out, it is probable that the eggs 

 captured by them were all far advanced in development, if the larvae had not 

 already hatched out. The sheet of spawn found by Hjort and Murray on the western 

 side of the Atlantic was taken over water of considerable depths. It is stated by 

 these authors, however, that, since the Angler-fish only inhabit the coast banks, 

 the finding of slightly developed eggs that could not have been drifting many days 

 indicated that they were in the neighbourhood of the American coast bank. But 

 our knowledge of the distribution of the Angler on the American coast, and the fact 

 that these eggs were only slightly developed, may be held to prove that they were 

 shed in waters of considerable depths. The Angler on the western side of the 

 Atlantic belongs to the warmer waters. According to Goode and Bean, a speci- 

 men about four inches long caught on the Banks of Newfoundland is the most 

 northern recorded occurrence in the western Atlantic. 



The evidence from the Mediterranean is also all in favour of a deeper water 

 spawning habitat. There are no records of the occurrence of sheets of floating 

 spawn, or even of very early stages of Loj)hius in the inner region of the Adriatic. 

 The only records of spawn in the Mediterranean are got from Naples, which is near 

 to deeper areas. Even the spawn got at Naples contained embryos well advanced 

 in development. Again, in the Gulf of Trieste, which is very remote from the deep 

 water, only the older post-larval stages of the Angler were found, whilst in the 

 open sea of the Adriatic, less distant from the deep water, the earlier post-larval 

 stages were also captured. 



So far, the northern North Sea is the only area in which recently spawned eggs 

 of Lophius piscatorius have been captured. The known distribution of the adults, 

 the occurrence of sheets of spawn with embryos well advanced in development, 

 and of larval, post-larval, and bottom forms, together with the knowledge of the 

 adaptations of the young forms to a prolonged pelagic life, are facts which show 

 that the Northern North Sea is only a very subsidiary area for the spawning of the 

 species. The limits of the spawning area of Lophius piscatorius, however, cannot 

 be defined exactly from the present evidence, but a hypothesis may be advanced 

 which describes the isolated facts — a hypothesis which must be tested by future 

 experiment. 



Lopilnus piscatorius is a species which has its headquarters in the Atlantic. 

 On the European side, the species extends its range into the Mediterranean, North 

 Sea, Skagerrak, Cattegat, and Baltic. The Angler is very closely allied to Atlantic 

 species which belong exclusively to the deep-water, but Lophius itself is most 

 abundant in waters of moderate depths. Its extreme bathymetric range is, however, 

 somewhat extensive ; it has been taken in depths of over 300 fathoms, and it is 

 also found in large numbers in the shallow coastal waters. Its extreme limits of 

 distribution are, therefore, much wider than its spawning distribution, for it is 

 found very frequently in areas where it never spawns. Modifications in the adult 

 form are usually said to be adaptations for a life in the sea-weed or shallow water 

 areas, but such structures may be equally effective for life in deeper waters. The 

 Angler does not spawn in the shallow coastal zone, but in moderate to deep water. 

 It is a species which spawns in the warmer waters, and suitable conditions are 

 foimd in the warm salt water of the Atlantic and Mediterranean, probably in the 

 neighbourhood of the continental slope, on the edge of the deep water. It spawns 

 on 'both sides of the Atlantic. On the European side, to the west of the British 

 Isles, these conditions are found only at a considerable distance from the coast, 

 whilst on the American side of the Atlantic, suitable spawning areas are much nearer 



