26 - Remarks on the Trilobite. 
the earliest example of an articulated animal found among the 
ancient inhabitants of our globe, and although in some few existing 
genera we find certain points of analogy in their organization, the 
whole race probably became extinct after the subsidence of the 
great coal formation. Dr. Buckland remarks, “ No trilobites 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 noticed in strata coeval with any 
of those that contain the remains of trilobites; so that during the 
long periods that intervened between the deposition of the earliest 
fossilliferous strata and the termination of the coal formation, the 
trilobites appear to have been the chief representatives of a class 
which was largely multiplied into other orders and families after 
these earliest forms became extinct.” 
From the multitude of trilobites and fragments of trilobites 
which have been discovered in different parts of the world, most 
of which present nothing but portions of the upper shell of the 
fossil, the discovery of the figure of the under side of the animal, 
and of the form and arrangement of the organs of locomotion, 
seems almost hopeless. As the solid parts of the animal strue- 
ture alone are for the most part susceptible of petrifaction, it is 
not to be expected the softer portions would leave any traces 
whatever in the rocks which have entombed and so perfectly 
preserved these ancient inhabitants of our planet; for these rea- 
sons, and some others which we shall presently mention, the legs 
of the trilobite have been supposed to be soft and very perishable 
paddles. 
Although much controversy formerly existed as to the true na- 
ture of the trilobite, it is now admitted by all naturalists to occupy 
a place among crustaceous animals. The existing genera t0 
which they are most analogous in their general structure are the 
serolis, the limulus, and the branchipus. In our monograph we 
announced the discovery of a recent trilobite in the southern 
seas, near the Falkland islands: this proves to be a species of the 
genus serolis established by Dr. Leach. In the configuration of 
its upper shell it approaches exceedingly near to that of some of 
the trilobites; the chief difference between the recent and fossil 
animal consists in the crustaceous legs and antenne of the serolis. 
The analogies existing between the limulus and our fossil, as We 
mentioned in another place, have been shown by Dr. Dekay 
others. 
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