Abstracts of Foreign Memoirs. 161 
within; even the fins, the anal one in particular, being indicated by 
projections of the surface, so that the external form of the con- 
cretion is plainly due to the contained fossil. On the other hand, a 
broad very flat concretion, with an irregularly rounded circumference, 
contained some vertebrae and other bones of the same Fish. 
4, Voldia (Leda) pygmea; in one case associated with an Anne- 
lid, in another with a Fish. 
5. Ophiura Sarsii; one specimen in a thin flat concretion, slightly 
convex on both sides, and which, though very hard, seemed less 
calcareous than usual, and was internally of a lighter colour and 
contained much mica. ‘The circumference was prolonged into five 
flat points of different sizes, but corresponding to the arms, and 
presenting some of the spines and plates, from the form of which the 
species is determined. Judging by the thickness of the arms, this 
specimen must have been as large as or larger than those found living 
by Dr. Sarsin Finmark; and had fully attained the size of the living 
Greenland form, which, according to Liitken, has a body 27 mm.=1°1 
inch in diameter. Here, as in the case of the Fishes, the form of the 
concretion was obviously determined by the shape of its contents ; and 
here, therefore, we have a further illustration of the singular manner 
in which, during the process of decomposition, the particles of car- 
bonate of lime contained in the clay were drawn together by the 
influence of the organic body, and concentrated around it in a 
hardened mass. 
Among other facts of interest which Dr. Sars mentions in con- 
nection with the Glacial formation is the distinct diminution south- 
wards of the Arctic character of the strictly Arctic Shells present in 
the clays. As they extend further south they fall off both in fre- 
quency and in size. Thus the Siphonodentalium vitreum is found 
living in Finmark and fossil as far south as Christiania ; and the living 
specimens from the north and those fossil from the south of Norway 
agree very closely in size, being from 2 to inch (10 to 12 mm.) long, 
by > inch (25 mm.) broad at the base, whereas the fossil specimens 
from further north, in the neighbourhood of Trondhjem, are + inch 
(20 mm.) long, and + inch (83 mm.) broad, and some seem to have 
attained even 1 or 11 inch in length, and } inch in breadth. 
On the other hand, it is a very curious fact that some shells 
extended further north in the Glacial epoch than they do now; thus 
Scrobicularia piperata, which has never ina living state been found 
further north than Floré in the Bergenstift, appears in the Glacial 
Clay at Surendal and at Trondhjem. Pecten maximus, too, which is 
unknown living further north than Christiansund, is found in the 
clay at Steenkjer, at the very head of the Trondhjem Fjord, and 
sixty miles north of that town. 
Sacero suLLA Costiruzionn GroLocicaA DELLA PRovinctA pI Prsa; del Prof. Cav. 
Paort Savi. 1863. 4to. Pisa. pp. 42, 
HIS account of the Geology of the neighbourhood of Pisa by its © 
veteran Professor is accompanied by an elaborate general map, 
with excellent sections, and special maps of the neighbourhood of 
VOL. I.—NO. IV. M 
