300 
line. This median portion of the medulla does not stain easily and has 
a bright appearance. I regard it as a network produced by the ramifi- 
cation of the processes of the various cells. Samassa has described 
the medulla as composed of three layers. The division, however, is 
not caused by a commissure, as in the brain, and I prefer to describe 
it as one mass, with the peculiarity above mentioned. 
Chicago, Ill., Jan. 1st, 1897. 
Literature cited. 
85. CARRIERE, Justus, Die Sehorgane der Tiere. Mit 147 Abbildungen 
und einer Tafel. München und Leipzig. 
’67. Miter, P. E., Danmarks Cladocera. Kjöbenhaven. 
791. Samassa, Paur, Ueber eigentiimliche Zellen im Gehirn von Leptodora. 
Anat, Anz., Bal 2, No.2: 
—  Derselbe, Unters. über das centrale Nervensystem der Cladoceren. 
Archiv für mikr. Anat., Bd. 38, pp. 100—141, Taf. V—Vil. 
’71. Weısmann, Ausust, Ueber Bau und Lebenserscheinungen von Lepto- 
dora hyalina. Zeitschr. für wiss. Zoologie, Bd. 24, No. 3. Mit 6 Taf. 
'90. WIEDERSHEIM, ROBERT, Bewegungserscheinungen im Gehirn von Lepto- 
dora hyalina. Anat. Anz., Bd. 5, pp. 673—679. 
Fig. 1. 
