514. F. G. SINCLAIR. 
are much more separate, and le almost on the same hori- 
zontal plane, the antennal lobe being anterior to the frontal. 
It is worth noting that, assuming St. Remy’s view of the 
primitive situation of the ganglia that make up the brain of 
Myriapods to be correct, this arrangement would be almost 
exactly the primitive one. There is also a consideration of 
interest in the disposition of the parts of the brain. If it is 
true that the arthropod brain has been derived from the 
development of an eliptical ring of nervous tissue, and that 
this condition is represented by the widely-separated nerve 
cords of Peripatus joined at the ganglia by commissures, 
then the structure of the brain of 8. evansi strongly recalls 
this condition, inasmuch as the ganglia on each side of the 
head are widely separate, and are joined by transverse 
commissures.! 
The brain of 8. modigliani (fig. 2), on the other hand, 
shows a concentration and compression that removes it from 
Class 3 altogether, and places it in the same class as that of 
the Julide. There is no separate commissure uniting the 
antennal lobe, but the two sides of the brain are united 
above the cesophagus by a broad tract of nervous tissue. 
This striking fact is not alone, for in the Craspedosomide 
we find a complicated brain of the same type as of that 
Glomeris. The Craspedosomideze are classed by 
Silvestri in the third of the five suborders in which he 
divides the Helminthomorpha (I. Diplopodi), and yet its 
brain is of the complex type of the third class (fig. 1), with 
the two commissures uniting the frontal and antennal lobes 
of the two sides. The species which | dissected is Craspe- 
dosoma polydesmoides. Polydesmus has a simple 
brain of the first class. Blanjulus guttulatus has a 
simple brain of the type of the Polydesmoidea. 
The brain of Platydesmus mexicanus occupies a large 
part of the head when we take into consideration the small 
size of the latter. It belongs to the first of my three classes, 
1 It is right to state that I had only a small amount of material of 8. 
evanst. 
