POINTS OF THE ANATOMY OF POLYXENUS LAGURUS. 108 
General Conclusions. 
The principal interest of Polyxenus lies in the likeness of 
some of the features of its anatomy to the anatomy of the 
Chilopods. While it agrees with the Chilognatha in the 
position of its generative organs and the duplication of some 
of its segments (the first four segments are provided with only 
one pair of appendages, the next four have two pairs, and the 
last one pair—Latzel and Bode), and in the fact that it is a 
vegetable-feeding animal, in connection with which fact its 
salivary glands are long and tubular, like those of other Chi- 
lognaths ; it nevertheless resembles the Chilopods in the form 
of its spermatozoa, which are long and filiform, and are con- 
tained in spermatophores; in the general structure of the 
segments, having the legs wide apart, with a ventral region 
between them ; and in the differentiation of the ventral nerve- 
cord. The single artery given off in each segment seems at 
first sight to afford a resemblance to the Chilopod circulatory 
organ, but I believe this resemblance to be superficial. In its 
essential characters the heart resembles that of the Chilognaths, 
and remembering that the Chilognath heart is formed by the 
confluence of spaces in the tissues of the body, the formation 
of the arteries is not a deep-seated character. 
Characters peculiar to itself are the peculiar form of the 
second pair of mouth appendages, and the absence of stink- 
glands and the substitution for them of numerous spines as a 
means of defence. 
In a former paper (5) I advanced certain views about the 
phylogeny of Myriapods, and came to these conclusions :— 
First, that Myriapods were descended from some Peripatus- 
like ancestor; secondly, that the Chilopods and Chilognaths 
branched off from some common ancestor, not differing much 
from the fossil Archipolipoda. Now the characters in which 
Polyxenus resembles the Chilopods are characters common to 
the larval Julus, and to the Archipolipoda (5). With regard 
to the absence of stink-glands, and the substitution of spines 
arranged in tufts over the body, I found in Julus that the 
