No. 2.] EPIPHYVSIS OF TELEOSTS AND AMIA. 261 
SUMMARY. 
If the foregoing description of the epiphysis is correct the 
following facts seem to me to be established : — 
1. There are two epiphysial outgrowths from the roof of the 
primary fore-brain of Salmo, Catostomus Stizostedion, Lepomis 
and Amia. 
2. These outgrowths form structures that become entirely 
independent of one another. 
3. They are histologically distinct from the choroid plexus. 
4. The distal part of the epiphysis contains many nerve- 
cells arranged in characteristic groups. 
5. The nerve-cells in the distal part of the epiphysis are 
connected with the brain-roof by a tract of nerve-fibres. 
6. This tract passes to the posterior commissure, 
7. The anterior epiphysial vesicle is rudimentary. 
8. There is in Amia a structure comparable to the paraphysis 
of other writers (Selenka, Eycleshymer). 
The following conclusions seem to me warranted by the facts. 
g. The anterior epiphysial vesicle of the Teleosts named 
above and of Amia is homologous with the parietal eye of 
Lacertilia. 
10. The posterior epiphysial vesicle (epiphysis) of the 
Teleosts named and of Amia is homologous with the epiphysis 
of Lacertilia. 
11. It is probable that in their primitive position the two 
vesicles were side by side. 
12. The “paraphysis” of Amia may be explained as a 
portion of the roof of the thalamencephalon, which has been 
isolated and has taken on a tubular form owing to the forma- 
tion about it of the choroid plexus. 
13. A study of the epiphyses of the larvae of Petromyzon 
with special reference to their connection with the brain is 
likely to yield results of great importance in settling the 
question as to whether the epiphyses were paired ancestral 
sense organs. 
ANN ARBOR, July 15, 1892. 
