THE BASIN OF THE ATLANTIC. 263 



— every where. Even wlien they yield nothing, the negative fact 

 is of value." 



757. Here, again, we perceive these little conservators of the 

 sea at work. This specimen that Brooke has obtained for us 

 comes from the coral regions, and the task of secreting the calca- 

 reous matter from the sea- water appears to have been left by these 

 little mites of creatures* to the madrepore and shell-fish, while 

 these mites themselves und-ertook the hard task of getting the si- 

 licious matter out. The division of labor among the organisms 

 of the sea is wonderful. It is a great work-shop, in which the 

 machinery is so perfect that nothing ever goes wrong. 



758. Specimens of the " ooze and bottom of the sea" have also 

 been obtained by the ingenuity of Brooke from the depth of 2700 

 fathoms in the JSTorth Pacific, and examined by Prof. Bailey, f 



* Mauey's Sailing Directions, 7th edition, p. 155. 



t " West Point, N. Y., January 29, 1856. 



" My dear Sir, — I have examined with much pleasure the highly interesting speci- 

 mens collected by Lieutenant Brooke, of the United States Navy, which you kindly 

 sent me for microscopic analysis, and I will now briefly report to you the results of 

 general interest which I have obtained, leaving the enumeration of the organic con- 

 tents and the description of new species for a more complete account, which I hope 

 soon to publish. The specimens examined by me were as follows, viz. : 



"No. 1. Sea bottom, 2700 fathoms ; lat. 56° 46' N., long. 168° 18' E. ; brought up 

 July 19, 1855, by Lieutenant Brooke, with Brooke's lead. 



'' No. 2. Sea bottom, 1700 fathoms ; lat. 60° 15' N., long. 170° 53' E. ; brought up 

 as above, July 26, 1855. 



" No. 3. Sea bottom, 900 fathoms ; temperature (deep sea) 32°, Saxton ; lat. 60° 

 30' N., long. 175° E. 



" A careful study of the above specimens gave the following results : 



*' 1st. All the specimens contain some mineral matter, which diminishes in propor- 

 tion to the depth, and which consists of minute angular particles of quartz, hornblende, 

 feldspar, and mica. 



" 2d. In the deepest soundings (No. 1 and No. 2) there is the least mineral matter, 

 the organic contents, which are the same in all, predominating, while the reverse is 

 true of No. 3. 



" 3d. All these specimens are very rich in the silicious shells of the Diatomacese, 

 which are in an admirable state of preservation, frequently with the valves united, 

 and even retaining the remains of the soft parts. 



" 4th. Among the Diatoms the most conspicuous forms are the large and beautiful 

 disks of several species of Coscinodiscus. There is also, besides many others, a large 

 number of a new species of Rhizosolenia, a new Syndendrium, a curious species of 

 Chaetoceros, with furcate horns, and a beautiful species of Asteromphalus, which I 

 propose to call Asteromphalus Brookei, in honor of Lieutenant Brooke, to whose in- 



