775 
Top.—Calcareous conglomerate, containing Turbo rugosa in great 
abundance. 
Laminated marls in which fossils are sometimes numerous, but at 
this locality they are wanting. 
Coarse sand, inclosing species of Pecten, Turbo, Echini, and corals 
in great confusion and seldom perfect. 
Fine sand from which the author procured only a species of 
Venus. 
Marls without fossils, at this point sometimes indurated. 
Greenish sand. 
Fine brownish sand with numerous fossils. 
Total thickness about 300 feet. 
In the deposits along the north shore Mr. Spratt procured no fos- 
sils, though he very closely examined Mount Paradiso and Philielmo. 
The strata in these hills and in that overhanging Tholo and Soronee 
dip at a considerable angle to the north; and exhibit the greatest 
visible thickness of the tertiary deposits, Paradiso, the highest, having 
an altitude of 920 feet ; but in the basin of Archangilo they attain 
nearly the same vertical dimensions. 
The tertiary strata are apparently continuous along the north coast, 
so that no defined margin between the supposed western lacustrine 
deposits and those of decidedly marine origin is indicated by an inter- 
vening ridge or formation of a different character. The long ridge 
of Skathee is considered however by the author a natural boundary 
between the basin of Palatshah and the eastern deposits, but he was 
unable to determine if the strata around Katavyah with which it is 
believed to be connected, contain marine or freshwater shells. 
There are also in several parts of the island elevated shingle beds 
of considerable thickness ; some of them, composed entirely of rounded 
limestone pebbles, occurring on the sides of the calcareous moun- 
tains ; while others consist of limestone and volcanic materials, and 
others again wholly of volcanic fragments. These accumulations, Mr. 
Spratt says, are evidently of two epochs, one anterior to the great 
volcanic era, and the other intermediate between it and the tertiary 
series, the sands and marls of that group being in several places 
around them. 
2. “ On the minute Structure of the Tusks of extinct Mastodon- 
toid Animals.” By Alexander Nasmyth, Esq., F.G.S. 
The author, at the commencement of his memoir, acknowledges 
his obligations to Dr. Grant for having first called his attention to the 
minute anatomical structure of the tusks of Mastodontoid animals ; 
and for having placed at his disposal a copy of the Swedish edition 
of Retzius’s demonstration of the typical structure of the dental or- 
gans of animals. 
Availing himself of the able tuition afforded by the Swedish Pro- 
fessor, Mr. Nasmyth says, he has prosecuted the subject, and that 
these inquiries, besides explaining to him the structure of that portion 
not completely investigated by Retzius, have unfolded to him some 
observations which are now generally acknowledged to be truths in 
