Organization of the Cyprides. 109 
ot our knowledge of the organization of the Crustacea, and it 
was easy to foresee that with the extraordinarily perfected 
methods of recent times, and especially the preparation of 
serial sections from hardened and stained objects, numerous 
gaps in our knowledge of these organisms would be filled up 
without much difficulty. Consequently I only supplied a 
pressing desideratum when I again took up the investigation 
of Cypris . The results obtained are briefly summarized 
here. 
1. The nervous system consists, besides the brain clothed 
with a thick ganglionic covering, of an elongated ventral 
cord containing five pairs of ganglia. The anterior section of 
the brain, representing the prosencephalon of the Arthropod 
brain, gives forth the nerves to the tripartite frontal eye and 
possesses a particularly strong coating of ganglion-cells, in 
which the centre of projection of the highest rank is probably 
to be sought. The mesencephalon gives off the nerves to the 
anterior antenna?, into which, however, fibres from the prosen- 
cephalon also enter ; at the sides of the metencephalon repre- 
sented by the exceedingly elongated commissures, which only 
unite far above the oesophagus, the nerves of the second pair 
of antennae originate. The ventral chain of ganglia extends 
throughout the length of the body to the sexual apparatus, 
and in its anterior, broader portion passes beneath the pro- 
jecting cariniforrn pectoral plate on the side of which the 
maxillae and maxillipeds (second pair of maxilla?) originate. 
This section contains the closely approximated ganglia of the 
mandibles, maxillae, and maxillipeds, the muscles of which 
are supplied by the nerves issuing from them. Beyond the 
pectoral plate commences the narrower and more elongated 
division of the ventral cord, the two ganglia of which give off 
the nerves to the pairs of legs. At the posterior of these 
terminates the cell-layer, which quite continuously coats the 
concentrated ventral cord, and the longitudinal fibres of the 
central mass are continued in two long median stems nearly 
touching each other, which ramify among the muscles of the 
abdomen. 
2. The frontal eye , as in all groups of Crustacea, is tri- 
partite and receives for each of its three divisions a nerve 
which is rooted in the median layer of the prosencephalon. 
Each of the three closely connected pigment-cups is occupied 
by some sixteen to twenty cells, into which the fibres of the 
nerve enter from the outside beneath a nearly spherical 
lens. Thus the eye, like the lensless median eye of the 
Cypridinae and Phyllopoda (Branchipus ) , is an inverse 
cup-eye. I have found no cuticular divisions such as occur 
