102 FREDERICK TILNEY AND LUTHER F. WARREN 



Differences observed in the epiphyseal complex in the various 

 species of ganoids already investigated 



1. Acipenser sturio, ruthenus, and rubicundus. Cattle ('82), 60 

 Goronowitsch ('88) ; 153 Garman ('96), 143 and Johnston ('01). 194 

 The conditions in these forms have been described above. 



2. Lepidosteus osseus. Balfour and Parker ('82). 12 The 

 pineal organ in this form was first mentioned by these authors 

 and later by Sorensen 363 in 1894, who described the structure as 

 having a distinctly saccular form. 



3. Amia calm. Goronowitsch ('88) 153 and Gage ('93). 135 

 Both of these authors showed that the pineal organ was a simple 

 sac in this species. Hill 180 in 1894 found in the embryonic stages 

 evidences of both parietal organs, namely, what he calls the 

 anterior epiphysis and the posterior epiphysis which probably 

 corresponded to the parapineal and pineal organs in Petromyzon, 

 while the anterior epiphysis is considered the homologue of the 

 parietal eye in Saurians. In the later embryonic stages the 

 connection with the brain of the anterior sac is lost. Finally 

 the pineal organ is pushed to the left side. Eycleshymer 112 

 found that the anterior organ has a lumen as late as the 15 to 

 16 mm. embryo. Nerve fibers were observed as late as the 

 12 to 13 mm. embryo going from the commissura habenularis to 

 the interior of .the anterior organ. Kingsbury 205 in 1897 observed 

 both the pineal and parapineal organs in the adult Amia. The 

 anterior organ was lying to the left of the pineal stalk and was 

 connected with the left habenular ganglion by means of a 

 thick, neural fasciculus. 



4. Polyodon folium. Garman ('96). 143 This species possessed 

 processes which look like nerve fibers. These processes go 

 from the interbrain roof and extend out to an end-sac deeply 

 situated in a parietal fossa of the skull. In one case only was 

 there a complete parietal foramen. 



5. Polypterus bichir. Waldschmidt ('87) 412 



6. Polypterus senegalus. Waldschmidt. 412 Both of these 

 species of Crossopterygii present a pineal organ which has a 

 tubular stalk and rises above the dorsal sac, first upward, then 

 turns sharply forward to end in a slightly dilated end-vesicle. 



