280 Scientific Intelligence. 
formity continues even to the era of the lower cretaceous deposits, 
when it began to be lost by the cooling of the earth ; the limits to re- 
gions presenting the same conditions as regards heat and other circum- 
stances, were thus contracted, and the fauna became diversified, being 
broken up into areas or basins of small extent. The cause of the 
strong line of division between the several formations, as indicated 
by the fauna, was some general catastrophe. The extinctions, more or 
less perfect, of races of fossils, were due to dislocations or disturbances 
of the earth’s surface. The elevation of the Andes was one of these 
catastrophes. : 
Previous to the cretaceous formation, the heat of the earth proceed- 
ing from the central heat, was such as to render null all the influence — 
of latitude in producing cold; and only subsequent to this period, has 
the last mentioned effect operated in localizing organic beings on the 
earth. 
25. M. Acassiz on the Geological Development of Animal Life, 
(Ann. Mag. Nat. Hist., xvi, 355, from Jahrbuch fiir Mineralog. Geolog., 
&c., Part 3, 1845.)—The Zoophytes, Mollusca, and Articulata existed in 
the earliest period of the earth’s development, although all their classes 
were not numerously represented in the oldest members; but they do 
not allow of our supposing that any progressive perfection to the pres- 
entcreation occurred. This is the case with the Vertebrata only, among 
which fish appeared in the first period, reptiles in the second ; mam- 
malia and birds did not appear for a long time after the former ; lastly 
came man, as lord of all: hence M. Agassiz denominates the corres- 
ponding periods, those of fish, reptiles and mammalia. 
The greatest change in the fish occurred at the end of the Jura pe- 
riod. All fish which existed prior to the chalk have a peculiar aspect 
and belong in general to extinct families; those of the latter epochs 
resemble those now living, and many of them belong to families and 
genera at present in existence; but they all differ specifically, just as 
all Vertebrata in different geological epochs differ in species. 
26. Fossil Shark, (Hybodus.)—(Quart. Jour. Geol. Soc., 1845, No. 
2, 197—with a plate.)—The entire mouth of a shark, partly open, has 
been found by B. Ibbetson in the Isle of Wight. The upper jaw meas- 
ured ten inches, and appeared to have carried twenty four teeth in 
the front series: The discovery decides a doubted point, that the 
teeth of the two jaws are similar in form. The Genus Hybodus 
attains its maximum expansion in the oolite, but ranges from the mus- 
chelkalk to the chalk inclusive. : 
27. Lower Green-sand Fossils.—A catalogue of the fossils of the 
lower green-sand in the museum of the Geological Society, is given in 
the London Quart. Jour. Geol. Soc.; No. 2, 1845, pp. 237-250. Some 
new species are described from the museum and other collections. 
