‘grees of longitude or about a thousand miles, is an ex 
Results of Microscopic Examinations of Soundings. 155 
Nos. 23 and 24 are similar in character to No. 22 but they 
yielded no globules of iron pyrites. 
me general remarks on the results of the examination of 
the specimens above referred to will now be given. 
__ Ist. The employment of acid enables me to correct an errone- 
ous statement which I made sometime since concerning the dee 
soundings of the Atlantic. Having at that time only a sma 
Portion of the soundings, and being unwilling to destroy a mor- 
sel of matters so precious, I did not apply acids, and hence over- 
looked the portion of mineral matter which though often very 
small is invariably present. 
nd. The mineral matter in these soundings generally shows 
no signs of abrasion, the sharpest edges and angles of even the 
Soltest minerals being retained. The minute size of the parti- 
cles and their sharp angular state appears to show that they 
been quietly deposited from gentle currents and not subse- 
quently disturbed. Even ihe coarsest and most abraded mate- 
th. These marls contain a great number of undescribed or- 
ganisms, both siliceous and calcareous. Many species which 
in Whe as far south as Florida and the Gulf of Mexico are found 
Mm the northern soundings above described, while some v - 
markable spécies found in the northern soundings have not been 
iti i The descrip- 
5th. Only a few i t casts of Polyth 
characterized pie ans have been detected in these north- 
*™ soundings, while their presence is rather the rule than the 
ae with regard to the southern soundings above referred to. 
. 6th. The occurrence of what appear to be volcanic products 
n the bed of the ocean for a distance of about twenty-two de- 
‘l= 
which deserves careful scrutiny. That any 
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