142 



ral Results of the Microscopical Examination of Sound- 

 ings, made by the U. S. Coast Survey off the Atlantic 

 Coast of the United States. By Professor J. W. Bailey, 

 of the Military Academy, West Point. 



1st, The most remarkable fact determined by the exami- 

 nation of the above-mentioned soundings is, that in all the 

 deep soundings, from that of 51 fathoms south-east of Mon- 

 tauk Point, to that of 90 fathoms south-east of Cape Hen- 

 lopen, there is a truly wonderful development of minute or- 

 ganic forms, consisting chiefly of Polythalamia, which occur 

 in an abundance rivalling those vast accumulations of ana- 

 logous forms constituting the marls under the city of Charles- 

 ton, S. C. 



2d, While there is a general resemblance between the 

 species found in all the deep soundings above mentioned, the 

 same species of Polythalamia occurring with few exceptions 

 at each locality, yet each place has its predominant species ; 

 thus in the most southerly sounding (H. No. 1, 90 fathoms), 

 there occurs a much greater number of Globigerina than in 

 any of the others ; while Textilaria atlantica, although pre- 

 sent, is by no means so abundant as in G. No. 8, 89 fa- 

 thoms. 



3d, Infusoria, as well as Polythalamia, occur in the deep 

 soundings ; but the Infusoria are few in number, and consist 

 of Coscinodisci, Galionella sulcata, and other species, which 

 probably swim freely in the ocean ; while none of the littoral 

 parasitic species, such as Achnanthes, Jsthmia, Biddulphia, 

 Striatella, and Synedra are found. 



4th, It is worthy of notice, that in the deep soundings not 

 a single specimen was found of Polythalamia belonging to 

 the Plicatilia of Ehrenberg (Agathistiques of D ? Orbigny\ 

 while a number of these forms were found in the shallow 

 soundings, and they arc well known to occur in vast quanti- 

 ties around the shores of Florida and the West India Islands. 

 Tli is group of Polythalamia appears to have been created 

 after the deposition of the chalk formation, in which no trace 

 of such forms occur, while they are very abundant in the 



