BibliograpJiical Notice. 225 



depths, enabling the creatures of the abyss to have the use of their 

 visual organs." 



Dr. Ehrenberg then enumerates the organisms which he has him- 

 self determined from the shallow and deep waters of oceans and 

 inland seas, namely : — I. (Independent organisms) 724 Polygastrica, 

 287 Polycystina, 585 Polythalamia, 22 Mollusca, 30 Pteropoda, 1 

 Annulatum, 2 Entomostraca, 6 Hadiata, 9 Bryozoa, 1 Anthozoum ; 

 II. (Xot independent, but named for convenience of rec».gnition) 

 226 Phytolitharia (including 142 Spongolitha), 50 Geolithia, 37 Zo- 

 olitharia, and 23 soft parts of plants. Of living marine shelled 

 animals [including Diatomaceae] thus observed, he reckons 1645; 

 and of the derivative forms mentioned above under the second head- 

 ing he has 336 ; altogether 1981. 



For the Xorth Polar Zone he has 71 definite organisms out of the 

 list, for the Xorth Temperate 918, for the Equatorial 487, for 

 the South Temperate 47, and for the South Polar Zone 24, the 

 greater numbers going with the larger researches. 



In six stages of depth from 101 to 20,000 feet the calculation 

 is as follows : — 



All observed 



Feet. Definite Forms. Organisms. 



101- 500 88 315 



501- 1000 72 240 



1001- 5000 141 437 



5001-10000 146 408 



10001-15000 130 344 



15001-20000 115 236 



The shallow-water forms are not here taken into consideration, as 

 freshwater organisms are mixed with them by geographical accidents. 



Ehrenberg points out that the abundance of independent forms 

 inhabiting the deep-sea bed is against the old notion, born of Bory 

 de St. Vincent, and resuscitated of late years, that a Hving pulp 

 pervades the sea and sinks in decay to the bottom ; nor, says he, 

 are the small the fry of the larger organisms. 



Prof. Ehrenbcrg's researches in microscopic fossils were begun in 

 183(5 (with sliced flint and semiopal) and 1838 (with the Chalk), and 

 are chiefly exhibited in the ' Mikrogeologie,' 1854. Enumerating 

 the subjects of these researches, he aiTives at the following numbers : 

 — independent forms, 1435; derivative fragments and parts, 172; 

 altogether 1607. Adopting the following five great periods, he 

 arranges his microscopic results * thus :-»— 



Definite All observed 



Forms. Organisms. 



Quaternary 419 652 



Tertiary . '. 362 807 



Chalk 292 445 



Jura 7 11 



Carboniferous and Grauwacke . . 52 60 



* In relation to this table of the geological distri()aution of Prof. 

 Ann. 6s Mag. N. Hist. Ser. 4. Vol. xi. 15 



