Systematic Position of the Trilobites, — Kingsley. 39 
point of view. Further it cannot be expected that students 
of Lang, Claus, and Lankester, will agree as to the value and 
significance of a number of important characters, or upon 
certain theories which have been the natural outcome of such 
differences. 
In the study of trilobite morphology and classification, I 
have made homologies and correlations from theories, opin- 
ions, and observations, which seemed most current and in gen- 
eral favor in standard text-books. The chief purpose of the 
investigation was to work out the structure and development 
of the trilobite and to apply the information to a classification 
of the members of the group itself. The results have been re- 
cently published in the Amer. Jour. Sci. (Feb'y and March, 
1897). No attempt was made to revise the classification of 
the animal kingdom from the trilobite standpoint, nor even to 
determine the branches of arthropod phylogeny. The discus- 
sion of the systematic position of Limnlus was carefully 
avoided, though this is usuallj'- considered the chief end of any 
trilobite theorizing. The altinities of the trilobites were man- 
ifestly closer to the Entomostraca and Malacostraca than to 
other arthropods, and therefore comparisons were drawn with 
these subclasses of the Crustacea. 
In the following remarks, only the main points of difference 
between the views held by Prof. Kingsley and myself are 
dwelt upon. 
If the trilobites are true crustaceans, as conceded, it is then 
fair to expect a more or less close agreement between the lar- 
val forms of both. In my paper on "The Larval Stages of 
Trilobites"' (American Geologist, Sept., 1895) I endeavored 
to show this close agreement, and concluded that the protas- 
pis stage of trilobites could be homologized with the nauplius 
larva of higher Crustacea. Prof. Kingsley notes the follow- 
ing differences : (1) the differentiated median and pleural re- 
gions; (2) the segmented cephalic region; (3) absence of 
median eye; and (4) paired eyes. 
As to the first, I do not think the differentiation is much 
greater than in the nauplii of Aims, Cyclops, Lucifer, and 
others in which there are side regions. The pleural regions 
cannot be considered as highly specialized characters, since 
they are common to many groups, and each segment is con- 
sidered as primarily consisting of terguiu, pleura, and sternum. 
