20 
enormous upthrows and downthrows which are met with in almost all 
parts of the world. 
For comparison I have brought some specimens of shells obtained from 
the deposit of the Avon dug out in making the new Dock entrance and 
used for filling up the Quarries on Durdham Down. They are mostly land 
shells but some of them betray a marshy situation. Many seem to be of 
the same species as those I found in the clay at Bideford Bay and 
moreover shells now found living on the banks of the Avon are as much 
larger in proportion than their sub -fossil representatives as are those from 
N. Devon. The neighbourhood of Bristol may be therefore supposed with 
reason to have undergone the same changes of level as the shores of North 
Devon and other parts of the S.W. of England. 
II. 
The British Fossil Entomostraca. 
Read at the Sectional Meeting on February 7th, 1872. 
By W. W. Stoddart, F.G.S., F.C.S. 
After describing the beauty of form, extraordinary configuration, and 
complexity of the many pieces forming the exoskeleton, the ancient 
existence of these curious animals was alluded to and the immense number 
in which they are found in the different stratified deposits. 
The Entomostraca are well adapted for the places in which they are 
found, some being free swimmers while others are contented with crawling on 
the mud, or hovering over the surfaces of plants. Some of them in the 
Palaeozoic period attained a considerable size, but most of the genera are 
minute, not measuring more than the fraction of an inch. 
The Entomostraca compose a sub-class of Crustacea ranging between 
the Cirrhopoda and Xyphosura. The name Entomostracon was first given 
by Muller in 1785. These animals differ from the ordinary Crustacea by 
having a carapace or valves under which the whole body and feet move 
with freedom, and possessing no true gills. Either some or all of the feet 
are expanded, and subdivided into an immense number of parts, covered 
with cilia so that a very large surface is exposed to the aerating medium. 
In a few genera the jaws are extended into a broad plate for the same 
purpose. This arrangement is beautifully shewn in the common Argulus. 
The Entomostraca are very cosmopolitan, abounding in fresh, brackish, or 
