914 Pineal Eye in Extinct Vertebrates. 
THE PINEAL EYE IN EXTINCT VERTEBRATES. 
BY E. D. COPE. 
ie discovery of the pineal eye in lizards is due to Leydig, who 
first recognized it as a probable sense organ in 1872. Dr. 
Graaf first determined its structural correspondence with the inver- 
tebrate eye in 1886. In the same year! Spencer examined a large 
series of Lacertilia, and pointed out the very diverse degrees of 
development of this organ presented by these reptiles. In 1882 
Prof. Rabl!Ruckhard refers to the large parietal foramen of Ichthy- 
osaurus and Plesiosaurus as indications of the existence of a pineal 
sense organ in those ancient reptiles, perhaps especially sensitive to 
temperature. In the NATURALIST for 1885 (p. 1029), the present 
writer stated that the Pelycosauria of the Permian epoch possessed 
large pineal eyes. Mr. Spencer expresses a similar opinion with 
regard to the extinct Stegocephala or labyrinthodonts of the carbon- 
iferous system, in his paper above mentioned. He there maintains 
also the homology of the median eye of the Tunicata with the 
epiphysis of the Vertebrata. 
In a paper published in the Naturauist of 1885 (p. 291), the 
present writer described the characters of the supposed fish Bothri- 
olepis canadensis, and homologized the orifice in the superior wall 
of the anterior part of the carapace (supposed to represent the head) 
with the orifice or mouth in a corresponding position in the Tuni- 
cata, especially referring to Chelyosoma, as having a general resem- 
blance to Bothriolepis. I mention (p. 290) that a plate covers the 
middle part of this orifice, forming a median valve of the mouth, a 
character which is also described by Whiteaves in 1887.2 It was 
already described in the allied Pterichthys by Pander and Owen. 
This plate covers the median part of the superior orifice, and leaves 
the lateral parts open. It has little fixity in the specimens I have 
examined, for which reason I called it a valve. See plate XV. 
Subsequently I described the genus Mycterops* from the coal 
1 Mr. tne paper is dated 1885, although he quotes De Graaf’s 
and my own papers published in 1886. 
ws Tlustrations of the fossil Fishes of the Devonian Rocks of Canada: 
Transac. Royal i p. 102. 
a ety of Canada, 1886 (7), 
* Arnarion) Naturalist, 1886, p. 10 029. 
