16 Notices of Memoirs. 
insatiate minds, a brief statement how far back an ‘ancestral’ 
lineage has extended, zoologically and stratigraphically, in order of 
time. Though it is not an easy task for any geologist to arrange 
chronologically the sedimentary deposits between the lowest accepted 
Silurian and the zone at which all differences of opinion cease as to 
the existence of life, merely because we have, as yet, in Britain 
discovered no trace of its existence. But confessedly there is an 
enormous lapse of time between these two limits; and, as an un- 
doubted discovery of life-remains has been made, very nearly upon 
the lower confines of the older series of strata, we may reasonably 
ask for search—a constant and active search—into rocks of ages 
intermediate in time. ; 
In the Longmynd rock, suggested to be of Cambrian age, near 
Church Stretton in Shropshire, Mr. Salter discovered some traces of 
vermicular life (Worm-burrows, ‘ Arenicolites’) and a fossil organic 
relic, supposed at first to belong to a Trilobite, but since dis- 
covered to be a part of the shelly covering of the extinct phyllopodous 
crustacean, Ceratiocaris. Several other endeavours have been made 
since to discover more, or even a correspondent fragment, of this 
ancient shrimp-like Crustacean; but even a pilgrimage undertaken 
by Prof. Morris and myself to the classical spot, to which we were 
. guided by Mr. Marston, of Ludlow, failed; for, although we broke a 
few hundredweights of the shaly stone of the mountain, no remains 
of the ancient crustacean rewarded our labour. Still I am con- 
vinced that at some future time the swelling hills of the Longmynd 
will disclose, to geologists who can spare more time to their inves- 
tigation, a more satisfactory account of those relics of ancient life 
which they undoubtedly contain. 
Here, then, studies open out to us which will repay those who 
take them up ; for what can be a grander thought for an enthusiastic 
field-geologist, who looks upon a mountain which he has formerly 
considered as of ‘granitic’ or ‘azoic’ age, than that such a monu- 
ment of the world’s existence contains, close-treasured within its 
rocky bounds, evidences of a more ancient life-light than that which 
had previously illumined the confines of his knowledge ? 
ABSTRACTS OF FOREIGN MEMOTRS. 
ree 
On Brackish WatrErRs AND THEIR Deposits. By Dr. Lorenz. (Proceed. Imp. 
Acad. Vienna, Dee. 10, 1863.) 
CCORDING to Dr. Lorenz’s observations in the Adriatic, espe- 
cially at the mouth of the Fiumara, fresh water poured into a 
tideless sea, somewhat deep near the shore, forms a rather limited 
brackish stratum spreading over the salt water in form of a wedge, 
the lateral planes of which at first converge in a steep and subse- 
quently in a very acute angle. At the mouth of the Fiumara, the 
horizontal extent of this wedge is to its initial vertical altitude as 
700 to 1. ‘The conditions at the mouth of the Elbe are quite differ- 
