H.. Woodward on a New Chart of Fossil Crustacea. 469 
extensive. Take, for instance, the Brachyura (the Crabs). At 
the present day they occur as terrestrial, freshwater, and marine 
dwellers ; whilst their remains go down into the Oolitic rocks, and 
occur in every higher formation, with marine and freshwater 
shells and leaves of land-plants; and their distribution may be 
exemplified by the curious fact, that for ages the Chinese have 
used the fossil Crabs from the island of Hainan in their Pharma- 
copeia as a highly esteemed medicine to remove ‘ heartburn’ and 
indigestion. 
On looking at the Chart, we shall perceive that it is divided both 
by transverse and vertical lines. ‘The transverse lines separate the 
several geological formations, whilst the curving vertical ones in- 
dicate the different zoological orders. 
We thus perceive, that of all the varied forms as we descend, 
when arrived at the oldest Silurian and Cambrian Rocks, only one, 
or at most two forms—Trilobites, and the bivalved and dish-shaped 
Crustacea (Phyllopods and Ostracods)—remain. 
But although, in certain rocks, Trilobites alone are found, yet 
their diversified forms and their extreme beauty of sculpture and 
ornamentation to a large extent compensate for the absence of 
higher orders, whilst their numbers would seem to have been in- 
credibly large; so large, indeed, that they have afforded subject of 
study to Barrande, Burmeister, Emmerich, Angelin Salter, and 
many other paleontologists. As this group ascends in time, we 
find those extravagantly ornamented and spinose forms such as 
Paradoxides and Acidaspis disappear, and only one genus, Phillipsia 
(named after the distinguished President of the British Association) 
survives to the Coal-measures, when the whole group disappears, and 
its place seems filled by Stomapods, Amphipods, and Isopods—forms 
to which Mr. C. Spence Bate has paid so much attention, and which 
in our Arctic seas attain as grand a development as did the Trilo- 
bites in the Silurian seas. 
It would be an interesting question to investigate, whether the 
climate of the Silurian period was one of extreme cold, like that 
of our Arctic regions, and what higher animals fed upon those 
myriads of Trilobites which swarmed in every sea; for there were 
no ‘ htight Whales’ in Siluria, as in the Arctic seas at the present 
day, to devour them, and we cannot rest satisfied with the notion 
that they were only the consumers and not the consumed, or with 
that suggested by an eminent Continental paleontologist, that ‘ they 
ate one another.’ 
The next oldest and most remarkable group is that of the Phyllo- 
poda and Ostracoda, the bivalved and dise- -shaped Crustacea which 
abound in the Shales of Lanarkshire and almost every higher forma- 
tion to the present day, often forming entire strata with their horny 
or shelly envelopes. This is the only group which seems to have 
been represented from the Cambrian Rocks to the present day. 
Perhaps the most extraordinary and extinct order is that of the 
Eurypterida, the largest individuals of which attained a length of 
6-7 feet, and are known to the Forfarshire quarrymen as the ‘ ‘Sera- 
