Limbs and Mouth-parts of Crustaceans and Insects. 419 
have myself also seen what 7s asserted; besides this I have 
several times refrained from giving a quotation when it 
appeared to me to be entirely unnecessary or when an author 
could not be quoted without lengthy explanations. Certain 
of the statements alluded to are already to be found in my 
memoir in “ Dijmphna-Togtet &e.” (especially in the French 
résumé of the paper), and are there accompanied by figures; 
in “ Cirolanidee .. .. Musei Haun.” some unimportant 
corrections are given. 
I. GENERAL OBSERVATIONS. 
1. It is probable that the appendages of the Crustacea 
primitively consist of an axial portion and two equivalent 
rami. On practical grounds, however, I employ the term 
endopodite for the axial portion and inner ramus, so that 
the outer ramus is considered as proceeding from one of the 
joints of the endopodite. 
2. By comparison of the limbs of the Aranee, Thely- 
phonus, Scorpiones, Chelonethi (Cheli’fer—Obistum), and 
Solifugee we soon discover that the segments, with the excep- 
tion of the two first, are not homologous one with another 
according to their parallel numbers (Gaubert). In order to 
determine the homology enumeration is not sufficient; we 
must in addition examine the form and length of the segments 
and especially the direction and form of the articulation. 
This conception, the correctness of which can easily be 
perceived in the case of Arachnida, is utilized in the case of 
the malacostracous Crustacea to deduce new results (§ 22). 
3. If we would arrive at a comprehension of the mouth- 
parts and limbs of Insects, Myriopods, and Crustaceans from 
a really morphological point of view, we must first study 
them in different types belonging to the last-mentioned class. 
4. In order to understand the structure of the maxille in 
the Malacostraca we must commence with the maxillipedes. 
For instance, in the case of the Isopods and Amphipods it is 
easy to see that the masticating-lobes, which arise from the 
inner side of the second segment or (in Gammarinz) from 
the second or third segment, are simple processes starting 
from the inner angle of the respective segments ; in Hurycope, 
for example, a lateral masticating-lobe of this kind is a simple 
prolongation, while in Ldothea entomon, on the other hand, it 
is divided off by a secondary articulation which has a certain 
ower of movement (vede “ Dijmphna-Togtet,” tab. xx.), 
Similarly the masticating-lobes of the two pairs of maxille 
must be regarded as processes from the sides of ane several 
32 
