PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 359 
curred in most of the deeper dredgings. Large quantities of a large, 
handsome, but very fragile, cup-coral (Flabellum Goodei V.) occurred in 
the deeper localities, especially at stations 880, 894, 895, but most of the 
specimens were ruined by being crushed by the great weight of the 
contents of the trawl]. The animal of this coral is bright orange, with 
a purple center. 
While many of the species of every class obtained here are arctic, or 
belong to the cold waters found at similar or greater depths on the coasts 
of Europe and in the Mediterranean, a few genera, like Avicula, Solarium, 
and Marginella, are related to southern or West Indian forms. A num- 
ber of the most abundant species of Crustacea and Echinoderms* had 
already been described from the collections made by Pourtales, off 
Florida. 
Many free-swimming species, belonging to the Pteropoda and Hete- 
ropoda, of which we dredged the dead but perfectly fresh shells, were 
not previously known to occur so far north. They were associated with 
others of the same groups which had previously been taken living at the 
surface along our shores, but they all belong properly to the Gulf Stream 
fauna. . 
The frequent occurrence of nearly fresh shells of Argonauta Argo was 
also a matter of surprise to us, and indicates that this species must 
often be very common hear our coast. 
The very large collections of specimens obtained on these three trips 
have, as yet, been only partially examined, but enough has already been 
done to prove this region to be altogether the richest and most remark- 
able dredging ground ever discovered on our coast. The large number 
of new forms, combined with others previously known only from remote 
regions, constitute a very distinct fauna, hitherto almost wholly un- 
known. 
A considerable number of undetermined, and perhaps undescribed, 
shells from these localities are not included in this article. 
* A brief account of the Echinoderms obtained by us, with descriptions of several of 
the new species discovered, has been published by me in the American Journal of 
Science for November, 1880. 
It is only necessary to say here that several of the star-fishes, Ophiurans, and Crin- 
oids occurred in such large numbers as to constitute one of the most conspicuous 
features of the fauna. The most abundant species were Archaster Americanus V., A. 
Agassizii V., A. Flora V., Luidia elegans Perriér, Ophiocnida olivacea Lym., Ophioscolex 
glacialis M. & Tr., Ophioglypha Sarsii Lym., Antedon Sarsii (D. & Koren). 
All these species, except the last two, are orange-colored, varying to orange-red. 
The same is true of Acanella Normani, of most of the Actinians, and of the majority of 
the crabs and shrimps, as well as of some of the fishes, It seems probable that the 
prevalence of orange and red colors among the deep-water animals is due to the fact 
that the luminous rays of those colors are completely absorbed by the thick, overlying 
stratum of sea-water, and consequently these animals, not being capable of reflecting 
such bluish and greenish rays as do reach them, would be nearly invisible at those 
depths beyond which white light penetrates. If this be true, such colors, being pro- 
tective, may be due to the operation of natural selection, according to the principle 
so often exemplified in shallow-water animals having colors like their surroundings. 
