PALEONTOLOGICAL GEOLOGY , 321 
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PALEONTOLOGICAL GEOLOGY 
Anatomy of Early Trilobites. Out of the wealth of finely pre¬ 
served trilobitic remains recently unearthed from the Burgess 
Shales of the Mid Cambric section above timber line on Mount 
Field, in the southwestern part of British Columbia, there are a 
number ofi specimens which display the ventral appendages and 
other little understood structures of these organisms. 
The appendages of these animals are preserved almost with 
the same distinctness as those of the crustaceans of modern seas. 
One of the Burgess shales forms is Rominger’s Neolenus serratus. 
This trilobite had a singularly thin test. As compared with that 
of the common King crab of modern waters it had about the 
same thickness in individuals of like size. The test of the axial 
and pleural lobes of Neolenus was reinforced by rounded ridges 
and local thickenings that gave it notably increased strength. 
Connection by muscles with the ventral integument gave it a rigid¬ 
ity that would withstand relatively great strains without flexing 
or breakage. With the muscles of the coxopodite extending 
through the ventral integument to the strong axial process the 
base of the limb had firm support. 
The animal could thus use its legs to walk clear of the sea- 
bottom, or to push its way through the soft bottom mud and 
sand as it searched for food; or it could sink or emerge from the 
bottom ooze very much as does the Limulus of today. 
One structure is of especial significance. Presence of epipo- 
dites on the limbs of Neolenus being challenged special examina¬ 
tion of this feature was instituted. Their existence was corrobo¬ 
rated by Messrs. Ulrich, Ruedemann and Bassler. 
“The surface of the epipodites exhibits no trace of the trans¬ 
verse inosculating lines which are generally present on the exopo- 
dites, being so far as these wrinkles are concerned, entirely smooth 
