312 THREE CRUISES OF THE “ BLAKE." 
Among the actinians brought up from deeper water, red, 
orange, or rosy and flesh-colored tints and stripes axe as abun- 
dant as in the more common species of shallow water. The 
dominant colors of gorgonians are orange, red, green; violet, 
yellow, fully as varied an assortment as exists in the anthozoa 
of a flourishing coral reef. 
The number of species of crustacea (schizopods, peneids, cari- 
dids) colored a brilliant scarlet is quite large, and it is somewhat 
remarkable, as has already been noticed by Moseley, that a pig- 
ment which is seen occasionally in some of the more minute 
pelagic crustacea should be so abnormally developed in deep 
water. 
In other deep-sea crustacea there is a predominance 
of shades of yellow, pink, and pale greenish tints. 
Large masses of sponges of a brilliant orange -yellow or 
brownish pink are constantly dredged from depths near the two- 
hundred-fathom line, associated with species having the colors 
of the littoral sponges. 
In the deep-sea comatulæ the coloring 
is similar to that of the shore species. 
reddish yellows, and browns, the prevailing tints. 
We have violet, green, 
Among’ the 
stalked crinoids the tints vary from cream-colored to dark green 
or grayish violet. 
The coloring principle, pentacrinin, dissolved 
in alcohol, produces an intense purple red. 
The distribution of marine plants! plays an important part 
1 The recent observations of Berthold 
in regard to the bathymetrieal range of 
alge indicate clearly that the principal 
features in their distribution are light 
and the motion of the water. The species 
characteristic of localities exposed to 
violent action of the waves are differ- 
ent from those found in more protected 
places. There are alge which require 
intense light, and others which flourish 
best in sites sheltered from direct action 
of the sun. 
The green and brown alg: need the 
greatest amount of light and motion, 
and flourish in those limits of the shores 
which are closest to the high-water mark, 
while on the contrary the red algs live 
in deeper water, where the light is more 
diffuse, and the motion somewhat les- 
sened. The calcareous alge thrive in 
quiet waters, though they are not, at 
least in the tropics on reefs, affected un- 
favorably by a flood of light. Berthold 
states that they are still found in great 
quantities in deep water, — sixty fath- 
oms in the deepest parts of the Gulf 
of Naples. The intense light and heat 
of the tropical seas may perhaps be the 
primary cause of the absence of an ex- 
tended marine flora. Yet light and heat 
are most important to the extensive pe- 
lagie flora, and in the tropical regions in 
the track of oceanic currents there are 
vast fields of surface alge, often dis- 
coloring the sea for miles. The fullest 
development of our coast alge undoubt- 
edly takes place in the temperate regions, 
and the fact that some of the larger 
fronds of Maerocystis have a length of 
150 fathoms, and that some of the eal- 
