312 THREE CRUISES OF THE " BLAKE." 



Among the actinians brought up from deeper water, red, 

 orange, or rosy and flesh-colored tints and stripes are 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 - yeUow or 

 brownish pink are constantly dredged from depths near the two- 

 hundred-fathom line, associated with sjDecies having the colors 

 of the httoral sponges. In the deej)-sea comatulse the coloring 

 is similar to that of the shore species. We have violet, green, 

 reddish yeUows, and browns, the prevailing tints. Among the 

 stalked criuoids the tints vary from cream-colored to dark green 

 or grayish violet. The coloring principle, pentacrinin, dissolved 

 in alcohol, produces an intense purj^le red. 



The distribution of marine plants ^ plays an important j)art 



^ The recent observations of Berthold quiet Avaters, though they are not, at 

 in regai'cl to the bathymetiieal range of least in the tropics on reefs, affected un- 

 algje indicate clearly that the principal favorably by a flood of light. Berthold 

 features in their distribution are light states that they are still found in great 

 and the motion of the water. The species quantities in deep water, — sixty fath- 

 characteristic of localities exposed to oms in the deepest parts of the Gulf 

 violent action of the waves are differ- of Naples. The intense light and heat 

 eut from those found in more protected of the tropical seas may perhaps be the 

 places. There are algse which require primary cause of the absence of an ex- 

 intense light, and others which flourish tended marine flora. Yet light and heat 

 best in sites sheltered from direct action are most important to the extensive pe- 

 of the sun. lagic flora, and in the tropical regions in 



The green and brown algte need the the track of oceanic currents there are 



greatest amount of light and motion, vast fields of surface algae, often dis- 



and flourish in those limits of the shores colormg the sea for miles. The fullest 



which are closest to the high-water mark, development of our coast algie undoubt- 



while on the contrary the red algse live edly takes place in the temperate regions, 



in deeper water, where the light is more and the fact that some of the larger 



diffuse, and the motion somewhat les- fronds of Macrocystis have a lengtli of 



sened. The calcareous algse thrive in 150 fathoms, and that some of the cal- 



