48 



FREDERICK TILNEY AND LUTHER F. WARREN 



ganglion, a pineal organ consisting of an end-vesicle, stalk and 

 proximal portion, and finally the posterior commissure. 



39 



Fig. 15 Mesial view of brain reconstruction of 100 mm. Mustelus. X 25. 

 The unshaded area shows the cut surfaces of the reconstruction. According 

 to Tilney, 1915. 



2, chiasmatic process; 3, cerebellum; 4, chiasm; 7, epiphysis; 13, infundibular 

 process; 14, infundibular process, saccular surface; 15, infundibular process, pitui- 

 tary surface; 20, lamina terminalis; 24, midbrain; 27, mammillary body (post- 

 erior lobe) ; 32, post-chiasmatic eminence (lobus inferior) ; 33, post-chiasmatic 

 recess (recess of inferior lobe); 36, post-infundibular evagination; 39, paraphysis; 

 40, recess of infundibular process; 41, supra-optic crest; 42, supra-optic recess; 

 44, telencephalon; 47, velum transversum. 



3. The development of the epiphyseal complex in ganoids 



Kupffer 223 1893 gave the first detailed description of the develop- 

 ment of the epiphyseal complex in Acipenser. The anlage of the 

 organ he describes as a small single evagination which later 

 becomes a stalk with an end-vesicle. Kupffer could find 

 nothing of the anterior or parapineal organ. Owsiannikow 

 ( J 88) 295 gave a description according to which in the three- or 

 four- weeks old embryo of Acipenser just in front of the pineal 

 organ there appears a small, round or cordiform structure.. 

 Hill 180 in 1894 described a small rudiment of the anterior or 

 parapineal organ in Amia calva. In the 10 mm. embryo this 

 body was ovoid in form and situated immediately in front and 



