FOREWORD. 
By Charles Schuchert. 
Trilobites are among the. most interesting of invertebrate fossils and have long attracted 
the attention of amateur collectors and men of science. These "three-lobed minerals" have 
been mentioned or described in books at least since 1698 and now several thousand species 
are known to palaeontologists. To this group of students they are the most characteristic 
animals of the seas of Palaeozoic time, and even though they are usually preserved as dis- 
membered parts, thousands upon thousands of "whole ones" are stored in the museums of 
the world. By "whole ones" perfect individuals are not meant, for before they became 
fossils the wear and tear of their time and the process of decomposition had taken away all 
the softer parts and even most of the harder exterior covering. What is usually preserved 
and revealed to us when the trilobites weather out of the embrace of their entombing rocks 
is the test, the hard shell of the upper or dorsal side. From time to time fragments of the 
under or limb-bearing side had been discovered, first by Elkanah Billings, but before 1876 
there was no known place to which one could go to dig out of the ground trilobites retain- 
ing the parts of the ventral side. 
Students of trilobites have always wanted specimens to be delivered to them weath- 
ered out of the rock by nature and revealing the ventral anatomy without further work 
than the collecting, but the wish has never been fulfilled. In the Utica black shales, near 
Rome, New York, there was finally discovered in 1S92 a layer less than ten millimeters 
thick, bearing hundreds of Triarthrus becki with most of the ventral anatomy intact. 
The collector's first inkling that such were present in the Utica formation came to him 
in a chance find in 1884, and for eight years he sought off and on for the stratum whence 
this specimen came. His long search was finally rewarded by the discovery of the bed, 
and lo! here were to be had, in golden color, prostrate specimens with the breathing and 
crawling legs and the long and beautifully curved feeling organs all replaced by iron 
pyrites. Fool's gold in this case helped to make a pak-eontologic paradise. The bed con- 
tained not only such specimens of Triarthrus becki, but also, though more rarely, of Cryp- 
tolithus tesscllaius and exceptionally of Acidaspis trentoncnsis. This important discovery, 
which has figured so largely in unraveling the evolution of the Crustacea and even has a 
bearing on that of most of the Arthropoda, was made by Mr. W. S. Valiant, then curator 
of the Museum of Rutgers College. 
There were, however, great material difficulties to overcome before the specimens 
revealed themselves with all of their information exposed for study. No surgeon was 
needed, but a worker knowing the great scientific value of what was hidden, and with end- 
less patience and marked skill in preparation of fossils. Much could be revealed with the 
hammer, because specimens were fairly abundant. A chance fracture at times showed con- 
siderable portions, often both antennae entire, and more rarely the limbs protruding beyond 
the test, but the entire "detail of any one limb or the variation between the limbs of the 
head, thorax, and tail was the problem to be solved. No man ever loved a knotty problem 
more than Charles E. Beecher. Any new puzzle tempted him, and this one of Triarthrus 
becki interested him most of all and kept him busy for years. From the summer of 1893, 
when he quarried out two tons of the pay stratum at Rome, until his death in 1904, his 
