THE BASIN AND BED OF THE ATLANTIC. 831 



Carolinas that Brooke's apparatus broiigbt up from tlie bottom of 

 the Atlantic off the Irish coast. 



617. Their suggestions. — The unabraded appearance of these 

 shells, and the almost total absence among them of any detritus 



more complete accoimt, which I hope soon to pubHsh. The specimens ex- 

 amined by me were as follows, viz. : 



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

 brought up Jiily 19, 1855, by Lieutenant Brooke, with Brooke's lead. 



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

 broxight up as above, July 26, 1855. 



" No. 3. Sea bottom, 900 fathoms ; temperature (deep sea)'320, gaxtou ; 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 

 proportion to the depth, and which consists of minute angular particles of 

 quartz, hornblende, feldspar, and mica. 



" 2nd. 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. 



" 3rd. AH these specimens are very rich in the silicious shells of the Diato- 

 macese, 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 Diatomes the most conspicuous forms are the large and 

 beautiful discs 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 cheetoceros, with furcate horns, and a beautiful species of 

 asteromphalus, which I propose to call Asteromphalus Brookei, in honour of 

 Lieutenant Brooke, to whose ingenious device for obtaining deep soundings, 

 and to whose industry and zeal in using it, we are indebted for these and many 

 other treasures of the deep. 



" 5th. The specimens contain a considerable number of silicious spicules of 

 sponges, and of the beautiful silicious shells of the polycistinese. Among the 

 latter I have noticed Cornutella clathrata of Ehrenberg, a form occurring fre- 

 quently in the Atlantic soundings. I have also noticed in all these soundings, 

 and shall hereafter describe and figure, several species of eucyrtidium, hali- 

 calyptra, a perichlamidium, a stylodictya, and many others. 



" 6th. I have not been able to detect even a fragment of any of the calca- 

 reous shells of the polythalamia. This is remarkable from the striking con- 

 trast it presents to the deep soundings of the Atlantic, which are chiefly made 

 up of these calcareous forms. This diflference cannot be due to temperature, 

 as it is well known that polythalamia are abundant in the Arctic Seas. 



" 7th. These deposits of microscopic organisms, in their richness, extent, and 

 the high latitudes at which they occur, resemble those of the antarctic regions, 

 whose existence has been proved by Ehrenberg, and the occurrence in these 

 northern soundings of spocies of asteromphalus and chsctoceros is another 

 striking point of resemblance. These genera, however, are not exclusively 



