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REVIEW OF THE PERMIAN FOSSILS. 
If we extend our review to the higher orders of creatures in the Permian system, 
we perceive that Trilobites are entirely wanting. Schlotheim alone has spoken of 
a fragment of a Trilobite in the copper slate of Saxony, but Count Munster has 
ascertained that this supposed Crustacean is an ichthyolite, belonging to his genus 
Janassa. The entire disappearance of these beings, so characteristic of the most 
ancient formations, is one of those striking phenomena to which we attach great 
importance. In the study of the palaeozoic succession we see, indeed, that the 
disappearance of this race is regularly announced, by a gradual diminution of its 
numbers during the preceding epochs. Appearing among the earliest forms of 
life and having their maximum of development in the Silurian period, Trilobites 
decrease very sensibly in the Devonian strata, and in the carboniferous deposits 
are reduced to some few small species, of which the Phillipsia and Griffithides 
(Portlock) are the last expiring forms. And here we are presented with one of 
those beautiful links in natural history, of which the strata forming the earth’s crust 
have afforded so many proofs ; for, with the final extinction of a family destined 
never more to reappear, its place is taken by an allied Crustacean, the Limulus, 
the earliest form of which was created during the formation of the great coal- 
fields, and was followed, in our Permian system, by the large and remarkable species 
as yet peculiar to Russia, the Limulus oculatus (Kutorga). Unlike the Trilobite, 
the Limulus has survived all the numerous revolutions which have followed its 
creation, and some of its species, far different indeed from the earlier types, are 
co-existent with our own race. 
Unfavourable as the conditions of life in Europe seem to have been, during 
the Permian tera, to many orders of Mollusca, and notably to the peculiar crusta- 
ceans called Trilobites, they were not antagonist to the propagation of aquatic Ver- 
tebrata. The fishes, which, commencing in the Upper Silurian rocks, obtained a 
great development in the Devonian and Carboniferous seras, hold a considerable 
proportion with reference to other classes in the Permian fauna. They are 
represented by sixteen genera including forty-three species, all of which, save one, 
are peculiar to the Permian deposits. The solitary exception is the Palceonis- 
cus Freislebeni (Ag.), which it is right to observe, has been detected at Ardwick, 
with granitic, eruptive and metamorphic rocks. This subject, embracing the discovery of many well- 
characterized Silurian fossils not hitherto observed in the Baltic provinces, together with well-recognized 
Devonian fishes and Carboniferous types, is mentioned at greater length in our Introduction, and will be 
again alluded to in the subsequent pages. (See Map). 
