432 



Messrs. Carpenter, Jeffreys, and Thomson [Nov. 18, 



remarkably so. A Munida, probably a variety of Munida Banffii, 

 somewhat paler in colour than usual, and somewhat slighter in its propor- 

 tions, which we met with abundantly in our northern dredgings, had re- 

 markably large eyes, very brilliant, transparent, and bronzy, giving the im- 

 pression of extreme sensitiveness. It is scarcely possible that any appre- 

 ciable quantity of the Sun's light can penetrate beyond two hundred fathoms 

 at most. The data with regard to the transmission of light through sea- 

 water are very scanty ; but the rapidity with which light diminishes during 

 the first few fathoms seems to point to its speedy extinction. It seemed to us 

 probable that the abyssal regions might depend for their light solely upon 

 the Phosphorescence of their inhabitants. The only use which the lower 

 animals make of light is to enable them to procure their food ; and it is 

 evident that in the night, or under any circumstances in which there is no 

 source of general illumination, it would answer the same purpose of guiding 

 them to their prey, if that prey itself w r ere luminous. Among the Star- 

 fishes the young specimens, 10 to 15 millims. from point to point of the 

 rays, appeared to be much more luminous than mature examples of the same 

 species. This is probably part of the great general plan which provides an 

 enormous excess of the young of many species apparently as a supply of 

 food ; their wholesale destruction being necessary for the due restriction of 

 the multiplication of the species, while the breeding individuals, on the 

 other hand, are provided with special appliances for escape or defence. It 

 is well known that fishes feed principally at night ; and the path of a shoal 

 of herrings may often be traced for miles by the broad band of phospho- 

 rescence caused by the glowing and scintillating of the myriads of phos- 

 phorescent animals, especially larva?, with which the sea is crowded, and 

 which supply their food. We can scarcely doubt that the phosphorescence 

 of the inhabitants of the dark abysses of the sea performs, in regard to the 

 great object of the supply of food, the functions performed in the upper 

 world by the light of day. 



57. On the 27th we dredged in 862 fathoms (Station 42), the weather 

 being still very fine, and the sea quite smooth. The bottom was ooze with 

 sand and dead shells. Among the Mollusca procured were a new species of 

 Plearonectia, Leda abyssicola (Arctic), Leda Messinensis (a Sicilian Ter- 

 tiary fossil), Dentalium gigas (sp. n.), Siphonodentalium (sp. n.), CeritJiium 

 metula, Amaura (sp. n.), Columbella Haliceeti, Cylichna pyramidata (Nor- 

 wegian and Mediterranean), and many dead shells of Cavolina trisjnnosa. 

 These latter were very common in all the northern dredgings, though 

 we never saw a living specimen on the surface. 



58. During the afternoon we took a series of intermediate temperatures, 

 at intervals of 50 fathoms, from the bottom at 862 fathoms to the surface. 

 The following Table gives the general results of this series of obser- 

 vations : — 



