36 Notices of Memoirs—Manzoni on Siliceous Sponges. 
the colder period when the flora at Moji flourished at the sea-level, 
whilst at the same time Northern Japan was probably invaded by 
plants from Amourland and Kamtchatka, some of which still exist 
in the Alpine flora of the tops of the mountains. 
Dr. Nathorst believes that a former land surface extended from 
Japan to the south-west, thus connecting it with Formosa and the 
Philippine Islands, and that the present flora of Japan is derived 
from that which lived on this now submerged area during the colder 
interval represented by the fossil flora of Moji, and that with the 
return of a warmer climate this flora again advanced northwards. 
Gade 
I1.—La Srrurrura Microscorica DELLE SPUGNE SILICEE DEL 
Miocene Merpio DELLA Provincra pi Botoana E pr Mopena. 
Per A. Manzoni. Con7 tavole. Bologna, Fratelli Treves, 1882. 
[The Microscopic Structure of the Siliceous Sponges of the Middle 
Miocene of the Provinces of Bologna and Modena. By A. 
Manzoni. With 7 plates. 4to., pp. 24. | 
N this interesting memoir Dr. Manzoni gives a very full and 
detailed description of the minute structure, the mineral state, 
and the conditions of deposition, of several species of siliceous 
sponges which he has discovered in the Italian Miocene. The 
sponges were derived from two localities, one in the neighbourhood 
of Montese, where they occurred in beds of dark argillaceous marls, 
intercalated in strata of coarse molasse or sandstone; in the other 
locality, in the hills of Zola, Guidoni, and Maserna, the sponges 
were imbedded in deposits of disintegrated siliceous, ochraceous 
material, traversed by layers and amygdaloidal masses of flint, 
which, like the Montese marls, intervene in the strata of the pre- 
vailing molasse sandstone. The sponges are so numerous in the 
siliceous and flinty layers that these may fairly be regarded as 
sponge beds. The author notices the occurrence of the siliceous 
sponges in conjunction with the flinty masses, which bear a great 
resemblance to the flints in the Upper Chalk, but as he has been 
unable to discover any traces of sponge structure in the amorphous 
masses of flint, he thinks that they cannot be derived, like the chalk 
flints, from siliceous sponges. He is, perhaps, unaware of the fact 
that in many places the flints in the chalk are quite destitute of any 
traces of the sponge spicules, and therefore the absence of structure 
in the Miocene flints by no means invalidates the probability that 
they have originated from siliceous sponges. 
The same species of Lithistid and Hexactinellid sponges occur 
in both the above-mentioned localities, but whilst those from the 
siliceous deposit retain a siliceous structure, though modified by 
secondary depositions of silica during fossilization, the sponges 
from the marly strata at Montese have had the silica replaced by 
calcite in the same manner as so many of the Hexactinellid sponges 
in the Jurassic Limestone of Germany. Another remarkable feature 
of these Miocene Hexactinellid sponges is the fact of their occurrence 
in a deposit, which, from its mechanical character and the included 
