PINEAL EYE 55 
eye, is now felt by the present writer to be more than ques- 
tionable. The remarkable pineal funnel of the Devonian 
Dinichthys (Fig. 134) is evidently to be compared with 
_the median foramen of Ctenodus and Paledaphus (=Sire- 
noids, p. 122); but this can no longer be looked upon as 
having possessed an optic function, and thus practically 
renders worthless all the evidence of a median eye pre- 
sented by fossil fishes. It certainly appeared that in the 
characters of the pineal foramen of Dinichthys there ex- 
isted strong grounds for believing that a median visual 
organ was present: its opening was in the pineal plate, 
midway between the orbits (PJ, Fig. 134). _ At the surface 
it was of minute size (X, Fig. 136), but below (Fig. 137) 
it flared out into a funnel-like form, shown in longitudinal 
section in Fig. 137 A. The peculiar character of this 
opening seemed to render it especially fitted for a visual 
function; the minute external opening forms an image 
near the plane of the visceral opening of the funnel, with- 
out the specialization of a lens, — an image so perfect that 
it might readily be photographed. It is evident, accord- 
ingly, that if an optic capsule were enclosed by this fora- 
men, it would have enabled its possessor to have looked 
directly upward and backward; and, without the need of 
developing lens-like and focussing structures, it could have 
readily received the images of all outer objects near or 
remote. 
But the function of this pineal foramen, unfortunately 
for speculation, could not have been optical. It occurs in 
a fish (7itanichthys) closely related to Dinichthys, and, 
J ___ as the writer * has recently found, is of a distinctly paired 
* He is obliged by accumulating evidence to abandon his former view that 
the pineal foramen of Dinichthys contained a specialized optic capsule (WV. Y. 
Rep. of Fisheries, 1891, pp. 310-314). 
