382 DR. ALLMAN ON THE ANATOMY AND PHYSIOLOGY OF CORDYLOPHORA. 
polypes a more or less perfectly developed mediisoid organization is required, this 
organization being demonstrable not only in the free medusoids themselves, which 
are occasionally observed to give origin to ova, but in those reproductive capsules 
and imperfectly developed medusoids which remain permanently adherent to the 
parent. 
Description of the Plates. 
PLATE XXV. 
Fig. 1. Cordylophora lacustris, attached to a dead valve of Anodon cygnem. Natural 
size. 
Fig. 2. A branch magnified with the polypes in various states of expansion, and with 
the reproductive capsules more or less developed. 
Fig. 3. Longitudinal section of polype to show the details of its structuie. 
a. Ectoderm. 
b. Polypary, 
c. Processes from the ectoderm attached to inner surface of the polypary. 
d. Endoderm. 
e. Mouth. 
/. Post-buccal cavity. 
s. Stomach. 
h. Common canal of the coenosarc. 
i. Muscles. 
PLATE XXVL 
Fig. 4. Portion of the walls of the stomach more highly magnified. 
a. Ectoderm, its cells containing thread-cells. 
h. Endoderm composed of elongated cells, with true secreting cells in then 
interior. 
c. Secreting cells with evident nucleus. 
d. Secreting cells with the nucleus obscured by the opake contents. 
e. Granular mass. 
/. Muscles. 
Fig. 5. Thread-cells previous to the exsertion of the filament. 
Fig. 6. Thread-cells after the exsertion of the filament. 
Fig. 7. A group of cells liberated under pressure from the ectoderm. Some contain 
a single thread-cell, others a nucleus-like body, probably an undeveloped 
thread-cell. They appear to have been originally contained as secondary 
cells within the proper cells of the ectoderm. 
