120 The American Naturalist. [February, 
Class IV, Myriapoda. 
Class V, Hexapoda. 
From this it would seem that the only conclusions which 
can be drawn are that, at least at this date, Professor Claus re- 
garded the Gigantostraca as a subdivision of the Crustacea, 
but was uncertain whether to regard it as equivalent to the 
Entomostraca and Malacostraca or not. 
It is impossible to give the views of Hatschek, as the part of 
his “ Zoologie ” treating of the Arthropods has not yet appeared. 
In his general table (’88, p. 40) he accepts, in a modified way, 
the Articulata of Cuvier, and regards the Onychophora as a 
class, of equal rank with the Arthropoda. 
The earlier studies of Boas upon the classification of the 
Crustacea possess such value that his general ideas upon the 
subdivisions of the Arthropoda deserve mention. In his 
“ Zoologie” (90) he adopts the following arrangement: 
Arthropoda. 
I Class, Crustacea. 
I Sub-Class Entomostraca, including as Orders: I, Phyl- 
_lopoda ; II, Cladocera; III, Xiphura (sic); IV, Tri- 
lobitæ; V, Ostracoda; VI, Copepoda; VII, Cirr- 
edia. 
II Sub-Class, Malacostraca. 
I Class, Myriapoda. 
(Peripatus doubtful.) 
II Class, Insecta. 
IV Class, Arachnida. 
Lang (’88) has the following classification : 
Arthropoda. 
I Sub-Phylum, Branchiata. 
Only class Crustacea. 
First “Anhang to Branchiata—Trilobita, Gigantostraca, 
Hemiaspide, and Xiphosura. 
Second “Anhang ”—Pantopoda. 
II Sub-Phylum, Tracheata. 
I Class, Protracheata. 
II Class, Antennata (Myriapoda and Hexapoda). 
III Class, Chelicerote sive Arachnoidea. 
“Anhang” to Arthropoda—Tardigrada. 
