SOME POINTS IN THE ANATOMY OF THE PLATYDESMIDm. 513 
In the simplest of these there is no optic lobe ; the frontal 
lobe is the most conspicuous part of the whole, the antennal 
lobe being small and inconspicuous, and lying below the 
frontal, while the circumcesophageal commissures start from 
the junction of the two lobes. ‘There is a distinct transverse 
commissure beneath the cesophagus, though it is neither so 
thick nor so far separated from the subcesophageal ganglion 
as in the more complicated brains. In this class of brain 
are included those of the Platydesmidez and the Poly- 
desmide. 
In the next class are included the brains of the Julide. 
The organ is complicated by the addition of optic lobes; the 
antennal lobe is more developed than in the first class, and 
the transverse commissure is larger. St. Remy’s figure of 
the brain of Julus maritimus is typical of the class. 
The last class is that typified by St. Remy’s figure of 
Glomeris. ‘lhe antennal lobe is much larger than in the 
foregoing, and more separated from the frontal. The mass 
of the brain is not continuous above the cesophagus, but the 
frontal lobes are connected by means of a commissure, as 
also are the antennal. The whole brain is less compact. 
These three classes of brains are not distinctly marked off 
from one another, but the interval between one class and 
another is bridged over by a number of intermediate forms. 
The greatest interval, as far as my limited experience goes, 
is between Classes 2 and 3. 
It is an interesting circumstance that the differences in 
the brain do not coincide with the great divisions of the 
Diplopoda as I expected that they would. ‘The most striking 
instance of this 1s in two species of Diplopoda from the 
Malay peninsular, Sphaeropoeus evansi and 8. modi- 
gliana (figs. 2 and 3). These two animals, closely related 
to one another by all the marks that are usually taken into 
account in the classification of the Myriapoda, have totally 
different brains. 8. evansi has a brain resembling the 
figure in St. Remys’ work of Glomeris, but shows a higher 
degree of differentiation. ‘lhe antennal and frontal lobes 
