304 Miscellaneous. 
B. Land-zonal periods. Zones of climate, continental climate, 
and unquict shallow seas. Plants and animals are developed on the 
increasing land; but in the sea they are changed or destroyed by its 
saltness, calcareousness, cooling, and restless surface. The continually 
increasing land-flora causes permanent rivers, hinders the passage 
of the clastic products considerably, favours their decomposition, and 
consequently the increase of salt and lime in the sea. With the 
development of terrestrial fauna and flora the proportion of carbonie 
acid in the air is raised, and land-plants increase. 8. Eighth, or 
dizonal-littoral (two-zoned littoral) period (Mesozoic). Broad mid- 
zone tropical; polar zones subtropical : 13-2 per cent. of salt in the 
sea. Flora and fauna more limited to the shore and neighbourhood 
of inland waters. 9. Ninth, or dizonal-continental period (Tertiary). 
Tropical mid-zone and temperate polar zones: up to 3 per cent. of 
salt in the sea. Flora and fauna more continental. The shiftings 
or derangements in the crust of the earth reach their maximum. 
The greater cooling causes great variability in plants. The origin 
of man, at first black only, dates from this 9th period. 10. Tenth, 
or three-zoned (trizonal) period (Quaternary). Hot, temperate, and 
cold zones. Development of the existing conditions. 
The main principles and very much of the details on which the 
foregoing classification of the geological periods and orders of nature 
has been founded by the author are treated of in Chapters ]V.—X1I, 
Thus :—the climatic interpolations of the geological periods, the pro- 
gressive salinity of the ocean, the absence of salt or muriatic acid in 
the inclusions of the last-formed primary quartz, the passing of 
fish from fresh to saline water, the sea containing in early times 
some phosphate of lime and more of lime than soda, the salinity of 
fresh water, geological time, the Caspian anciently freshwater, the 
gradual decrease of lime in the sea, carbonic acid in the economy of 
nature past and present, hypotheses of the developmental condition 
of early marine beings, the relationship of the oldest recognizable 
land-plants to sea-weeds, the genealogy.of the vegetable kingdom 
(table, p. 140), the differences between Monocotyledons and Dico- 
tyledons explained by their developmental history, carbonaceous 
sediments in the sea, proofs of the oceanic life-habits of all coal- 
making plants, and refutations of erroneous hypotheses of the for- 
mation of coal. This last subject is very fully treated in Chap. XI. 
under more than forty headings. Arguing throughout on premises 
of his own making, the author satisfactorily arrives at his own 
conclusions, which are far from being in accordance with the views 
of geologists and botanists of the present day. 
MISCELLANEOUS. 
On the Operculum of the Gasteropoda. By M. Hovssay. 
In 1825 Blainville wrote, in his ‘Manuel de Malacologie,’ as 
follows :— 
**The operculum is evidently the production of the skin which 
