512 F, G. SINCLAIR. 
Myriapoda up to the almost completely fused cord of Diplopoda. 
It does not necessarily follow that because one primitive 
character has persisted that therefore the Platydesmide 
and Craspedosomide are primitive types. It may be 
noted that the division of the zonite and the intercalated plate 
are present in all the somites except the telson. 
The ventral plate of the two species of Platydesmidez 
shows considerable differences. In kelantanicus between 
each pair of legs there is a sternal plate of peculiar form 
(fig. 17) with a sinuous anterior edge, and with the posterior 
edge curved so as to follow the curve of the outline of the 
coxee, with a blunt point projecting between the coxe of the 
pair behind it. On the median anterior region of this point 
there is a tubercle ending in a stout bristle. The bristle is 
perforated and in connection with the perforation there is a 
small mass of gland cells. The whole organ is shown in fig. 
19. The ventral plate of mexicanus is simpler (fig. 18) and 
without the organ. ‘lhe tracheal openings in both species are 
situated on the coxe and begin in the third somite, that is, 
not counting the trachez in the head. The tracheal openings 
(fig. 20) dilate into a wide pouch which runs some way into 
the body before giving off the trachee. 
Tur Nervous SYSTEM. 
Our knowledge of the nervous system of the Myriapoda is 
largely due to the excellent and accurate work of St. Remy 
(6). His work on the Myriapod brain was confined to two 
groups as far as the Diplopods are concerned; these are 
Glomeris and Julus. Both of these have eyes, and were 
selected with reference to the subject at which he was 
working, so that, for the purpose of comparing the brain of 
Platydesmu with that of other Myriapods, it was necessary 
to make a number of dissections of the brains of other 
species of Myriapods. The brain of Myriapods seem to 
fall naturally into three classes, types of which are shown in 
figs. 1—4, 
