332 ^''' S:. N. Moseley [March 5, 



no barriers to hinder migration. Mr. Agassiz has dredged off the 

 West Indies and the east coast of North America nearly all the 

 types obtained by the ' Challenger' all over the world. 



It is probably as correct to say that deep-sea animals have 

 colonized the shallower waters of the Polar regions as to say that 

 Arctic animals have occupied the deep sea elsewhere. 



There seems to be a close relation between the pelagic fauna and 

 deep-sea fauna. There are surface-swimming representatives of most 

 deep-sea forms. Ehizopoda both with calcareous and arenaceous tests 

 live abundantly in the deep sea, and Mr. Henry Brady concludes that 

 the Globigerina mud is formed by animals living at the bottom, the 

 pelagic representatives of these bearing but a small proportion to the 

 main mass. 



The most important question now remaining to be solved with 

 regard to deep-sea life is the range of life at the various depths 

 between the surface and the bottom of the ocean. At present nothing 

 is known with regard to this matter. Possibly there is a wide zone 

 between the surface and bottom devoid of life. The lecturer described 

 a net which he had devised, by which this question could be deter- 

 mined. By means of an electrical arrangement its mouth can be 

 opened and closed at will at any depth. Mr. Agassiz intends to make 

 use of it or some similar appliance. Some deep-sea animals possibly 

 pass their early stages of existence at the sea surface. 



The deep-sea basins being very probably of the remotest geo- 

 logical antiquity, it is remarkable that scarcely any ancient animals 

 occur amongst the deep-sea fauna. Almost all the most ancient forms 

 known are from comparatively shallow water ; for example, Heliopora, 

 Limulus, Lingula, Trigonia, Nautilus, Amphioxus, lampreys, ganoids, 

 and Cestracion. The deep-sea fish are of modern origin, allies of the 

 cod, salmon, and angler. Scarcely a single animal of first-rate zoo- 

 logical importance has been found in the deep sea. 



The deep sea was probably uninhabitable in early geological times, 

 being highly charged with salts and gases in solution and mud in 

 suspension, the results of its primitive superheated condition. 



The deep-sea animals must depend for sight entirely on the 

 phosphorescent light of themselves or others. The sense of touch is 

 probably mainly relied on by them. Investigations on their organs 

 of hearing might give valuable results. None have as yet been made. 

 The deep-sea animals are more abundant towards the upper limit 

 of their range ; the ultimate source of their food is the sea surface, or 

 derived from the land and shore. Their food is probably always most 

 abundant near coasts. 



Some animals are dwarfed, others enlarged by deep-sea conditions 

 of life. A Pycnogonid was obtained measuring two feet in length. 



The usual parasites have accompanied their hosts into deep 

 waters. 



Some deep-sea animals are brilliantly coloured, having retained 

 colours which were effective in shallow-water ancestors ; but colours 



