MUSEUM OF COMPARATIVE ZOOLOGY. 193 
The sections of the Trilobite retained in the slices of rock are trans- 
lucent, and in nearly all cases when used for illustration were photo- 
graphed by transmitted light. The photographs were used to obtain 
the outlines of the dorsal shell and appendages, thus insuring a greater 
degree of accuracy than enlargement by measuring. 
In referring to what has been done in the past, in the study of the 
organization of the Trilobite, it is unnecessary to present the many 
strange views that have been advanced to show that it was related to 
fish, mollusk, insect, or some crustacean to which it has but a superficial 
resemblance. These are given in the introduction to the-study of the 
“Organization of Trilobites,” by H. Burmeister, where the student 
can find the most complete review of the subject up to the date of the 
English edition (1846) that has been published. M. Barrande, in the 
Supplement to his Volume L, 1872, presents an historical review to 
that time. 
The following historical notes are given as showing that many 
naturalists have considered the Trilobite related to Limulus and also 
to the Phyllopoda as represented by Apus and Branchipus. 
1750. Ch. Mortimer, in the Philosophical Transactions (XLVI. 
p. 600), expressed the opinion that Scolopendræ aquatice scutato 
affine animal petrificatum (the Trilobite) appeared to correspond with 
Monoculus apus, Linn. 
1753. Linneus designated all the species belonging to the Trilobite 
as modifications of his Æntomolithus paradowus, deciding himself in 
favor of their near affinity to Monoculus apus. This view is expressed 
in all the editions of the “ Systema Nature.” 
1768. Ch. Fr. Wilkens sustained the views of Linnaeus, and gave 
the name Æntomolithus brachiopodus cancriformis marinus, thus 
removing the Trilobite from the domain of conchology, to which it had 
frequently been referred. 
1771. J. Imm. Walch adopted Wilkens's views, and, convinced of 
the unsuitableness of the name heretofore used, gave the name Trilo- 
bite, a designation that was generally received, and has since been used 
by authors with the exception of Dalman. 
1821. H. Burmeister says that “the year 1821 is a crisis in the 
literary history of the Trilobite, for a new epoch then commences,” 
V. Audouin and George Wahlenberg both arriving at very important 
results in their studies. Audouin summarizes his results in the follow- 
ing four conclusions, viz. : — 
ist. That Trilobites differ only from the other Articulata in points 
