FREDERICK TILNEY AND LUTHER F. WARREN 



that they would not prove wholly satisfactory for some of frhe 

 lower vertebrates. Earlier works on the pineal body, even 

 such as dealt with ichthyopsid and sauropsid forms, employed 

 the terms epiphysis and corpus pineale with so little discrimina- 

 tion that these definitions became rather vague. The com- 

 plexity of the structure in the lower reptiles, in amphibia, and in 

 li>h is such that it may only in a very general way be denomi- 

 nated the epiphysis. In the first place, many of the forms just 

 mentioned present, instead of a single epiphyseal process, two 

 well-marked structures projecting dorsad from the roof of the 

 iiiterbrain. Ontogenetically, both of these processes are con- 

 nected with the epiphyseal anlage, and yet if one of them were 

 called the epiphysis which should it be and by what term should 

 the other be designated? 



In a certain respect the suggestion of Hill ('91) m to call one 

 process the anterior epiphysis and the other the posterior epiphysis 

 has much to recommend it on morphological grounds. Unfor- 

 tunately, connotation has so rigidly associated the term epiphysis 

 with the much altered and modified conditions as they occur in 

 man and mammals, as almost certainly to lead to confusion in 

 the broader application proposed by Hill. More available, 

 although not without their defects, are the proposals of Studnicka 

 COG) 386 according to which the posterior epiphyseal process 

 becomes the pineal organ and the anterior process the parapineal 

 onjiui. The use of the term pineal at once reverts to the mam- 

 malian forms, for description of which it was first employed. 

 To apply this term, as, for example, in the fish where it has no 

 descriptive value, cannot be in accord with the best morphologi- 

 cal tendencies. Yet to Studnicka should be accredited the most 

 thorough and extensive consideration of this subject; his defini- 

 tions may, for this reason, be regarded as standards, especially 

 if the desire to avoid new terms is kept in mind. Accepting 

 Studnirka's terminology of an anterior process, the parapineal 

 organ, and the posterior one, the pineal organ, it is necessary to 

 recogni/e certain subdivisions in each of these organs. The 

 pineal organ has an end-sac, a x/r///,-, and a />r.r/i/i<il portion, the 

 latter in some cases i- connected with the rest of the interbrain 



