400 GEOLOGICAL SURVEY OF THE TERRITORIES. 
endite has its distinct blood passage, and thus respiration takes place 
all through the appendage. 
The nervous system.—The nervous system is quite uniform in the Phyl- 
lopods, and that of Limnetis has been described by Grube, that of Lim- 
-nadia by Klunzinger,* and more lately by Spangenberg, and that of 
Apus by Zaddach, while the brain and nervous cord of the young 
Branchipus stagnalis has been figured and described by Claus. 
Our Plate XXXL, fig. 8, copied from Grube’s drawings, illustrates the 
nature of the brain and nervous cord of the European Limnetis brachyura. 
The brain is very small, forming a single flattened mass from which the 
large optic nerves arise. The first antennal nerves arise from the begin- 
ning of the commissure, which forms an cesophageal ring, and the second 
antennal nerve arises opposite the transverse commissure, which com 
pletes the esophageal ring behind. Then succeed the peculiar ladder-like 
ganglionated ventral cord; from the two anterior ganglia arise respect- 
‘ively the mandibular and maxillary nerves, the third. pair of ganglia 
supplying the first beenopods. 
The anatomy of the nervous system of Limnadia hermanni has been 
fully described by Spangenberg,} but unfortunately he has given no 
illustrations. The following account is translated from his paper: 
“The nervous system of Zimnadia shows the greatest agreement with 
that of Apus. It has a primitive, embryonal character, as that of Apus. 
This is seen in the ganglions of the second antenne. These are in most 
Crustacea united in a common mass with the brain. In Limnadia not 
only the ganglion-swelling, but also the two transverse commissures 
uniting them preserve their original form, and the ganglion pair of the 
second segment differ here in no important point from that of the other 
segments, except in the lip-commissure springing from it. There also 
remain the ganglia of the ventral cord in the last body segment, both 
longitudinally and transversely well separated from each other, while 
in Branchipus and Artemia they are not more perfected, but in Apus 
suffer a widespread consolidation. 
“The central nervous system of Zimnadia consists, as that of all Phyl- 
lopods, of a two-lobed supracesophageal ganglion before the esophagus— 
scarcely properly called a brain—and right behind the esophagus, be- 
tween the digestive canal and floor of the body a ladder-like ventral 
chain of 26 ganglia, the tail segment being without a ganglion. 
“ Brain.—The supracsophageal ganglion consists of two spindle- 
shaped lateral lobes and one unpaired median section. All these pos- 
sess their own centers and send out the nerves originating from them. 
Such centers are five in all, four arranged in pairs in the lateral lobes, 
the fifth unpaired in the middle lobe. 
‘‘Of the two paired centers the foremost is by far the largest; it serves 
as the central organ for the optic nerve, the eye- -musele nerves, and 
furnishes the nervous tract reaching to the so-called larval eye. The 
smaller, situated somewhat farther ‘behind, lying under and external, 
sends fibers to the first antennal nerve. What significance the bean- 
shaped central body of the middle lobe, met with in all Phyllopods, has is 
not clear tome. It lies perpendicular to the longer axis of the animal in 
the hinder third of the middle lobe between the commissural threads 
passing from one lateral lobe to the other. From all sides pass curved 
nerve-fibers into it, which are variously covered and intertangled with 
one another. It consists quite unlike the paired centers “of large 
ganglion-cells, but solely of the so-called Leydig’s punctsubstanz, a con- 
fused mass of the finest fibers variously matted together. Whether, 
“See his figure in Sieb. u. K6ll. Zeits. w. Zool. XIV, Taf, XIX, fig. 26. 
{ Zeitschrift fiir wissensch. Zoologie. Supp. 1878 
