390 FOUND ONLY IN TRANSITION SERIES. 
No Trilob ites have yet been found in any 
strata more recent than the Carboniferous series ; 
and no other Crustaceans, except three forms 
which are also Entomostracous, have been no- 
ticed in strata coeval with any of those that con- 
tain the remains of Trilobites;* so that, during 
the long periods that intervened between the 
deposition of the earliest fossiliferous strata and 
the termination of the Coal formation,! the Tri- 
lobites appear to have been the chief representa- 
tives of a class which was largely multiplied into 
other orders and families, after these earliest 
forms of marine Crustaceans became extinct. 
The fossil remains of this family have long ' 
seems analogous to the recent discovery of similar fossils in the 
Transition rocks of Ireland, Germany, and the United States. 
The Fresh water fossils occurred near Potosi, at an elevation of 
13,200 feet. 
M. D’Orbigny’s specimens also confirm Mr. Pentland’s view, 
as to the analogies between the great Limestone formation of 
this district, and the Carboniferous limestones of England ; and 
as to the great extent also of the Red Marl, and New red sand- 
stone formations on the Continent of South America. 
* In Scotland two genera of Entomostracous Crustaceans, the 
Eui-ypterus, and Cypris, occur in the Fresh water lime-stone 
beneath the Mid Lothian Coal Field ; the Eurypterus at Kirkton, 
near Bathgate, and the Cypris at Burdiehouse, near Edinburgh. 
( Trans. Rorjal Soc. Edin. vol. xiii.) The third Genus, Limulus, 
has but recently been recognised in the Coal Formation, and 
will be described presently. The Entomostracans appear to 
have been the only representatives of the Class Crustaceans until 
after the Deposition of the Carboniferous Strata. 
+ Trilobites of a new species have lately been found in Iron- 
stone from the centre of the coal measures in Coalbrook-dale- 
Lond. and Edin. Phil. Mag. vol. 4. 1834, p. 376. 
