Zero of Animal Life probably about 300 fathoms.
The naturalists of our own time hold equal faith in the wonders of the sea, but seek therein rather for the links of nature's chain than for apparent exceptions.
I have in hands, now, specimens of bottom from t he Gulf Stream, obtained by Lieutenant Craven, and I can say that they are among the most interesting that I have ever seen.
The corals do not look much worn, but still appear to have been dead. There are some delicate shells of molluscs from depths beyond 500 fathoms, where they were certainly living.
Moreover, all our knowledge of organic remains teaches us, that species have a definite existence, and a centralization in geological time as well as in geographical space, and that no species is repeated in time.
As we descend deeper and deeper in this region its inhabitants become more and more modified, and fewer and fewer, indicating our approach towards an abyss where life is either extinguished , or exhibits but a few sparks to mark its lingering presence.