XX 
THE VOYAGE OF H.M.S. CHALLENGER. 
The observations of Donati ’ on the bottom of the Adriatic led. him to think that it is 
hardly different from the surface of the land, and is but a prolongation of the superposed 
strata in the neighbouring continent, the strata themselves being in the same order. 
They contain marble, stone, metals, and in some places sand, gravel, or clayey soil. He 
attributes to the nature of the sea-bottom the presence of certain substances in one 
j)lace and their absence in another, and adds that he thinks this observation will 
explain wliy the earth has mountains and plains entirely destitute of marine bodies, 
whilst in other parts a great many are found, and why in some spots many varieties are 
found, and only one in others. Among the rocks formed in the Adriatic, Donati mentions 
marble, breccia, and calaireous tufa. The bottom of the Adriatic is covered with a layer 
formed by crustaceans, testaceans, and polyps, mixed with sand, and to a great extent 
l)ctrified. This crust may be 7 to 8 feet deep, and he attributes to this deposit, bound 
together with the remains of organisms and sedimentary mineral matter, the rising of the 
bottom of the sea, and the encroachment of the water on the coasts. 
In the great works of Wolfgang, Knorr, and Walet (1755-1773) we akeady find a 
distinction established between the fossil remains of pelagic animals and those of 
animals found on the sea-coast, and they express an opinion that the existing analogues 
of those that have not been found must exist in the deep seas as yet unexplored. 
Beccari, towards 1729, created a new branch of conchology by the discovery of a small 
kind of jK)lythalamous shell of nautiloid shape {Nautilus heccarii, Linn.). The coils of 
the helix and its transverse divisions give it a great resemblance to the ammonite — a term 
of compari.son which was long adopted for all the other analogous Foraminifera, so 
jilentiful in the marls of North Italy. Beccari counted more than 1500 in two ounces 
of this micaceous silico-calcareous sand.^ 
leu years later G. Biauchi (better known by the name of J. Plancus) announced that 
he had found on tlie shore of Rimini the living analogue of the small fossil ammonite, 
and that its dimensions were such that it required 130 of them to equal the weight of a 
grain of wlicat. lie found a great many other species, which he still classed along with 
the nautilus and ammonite, on account of their internal divisions. His work^ contri- 
buted much to increase our knowledge on this subject, and at a later period he pointed 
out, within a mile of Sienna, a bed of microscopic shells analogous to those found on the 
shores of Rimini. 
Later on Soldani examined the clay of the tufa and sands of North Italy, and pro- 
duced hi.s work on the nautili and ammonites of Tuscany,^ enriching science with a 
' fvvJii *ur I'hiHtoire naturellc fie la incr Adrialifjue, par le Dr. Vitaliano Donati, avec une lettre du Dr. L. Sealer, 
trafluit (Ic I'lulien, & la Have, cliez Pierre de llondt, 1767, p. G. 
* Cunun. Donon., vol. i. p. 02. 
* I>e conchif iiiinua iiotin in littorc AriniinicnHi, Venice, 1739. 
* orittf>)(rarico e<l ofSi-rvazioni 8oi»ra]le terre nautiliche ed ammoniticbe di Toscana, with 25 plates, 
Kienno, M’*). 
