DEVELOPMENT OF THE BRAIN OF THE AMER- 

 ICAN ALLIGATOR: THE PARAPHYSIS 

 AND HYPOPHYSIS^ 



By albert M. REESE 

 Professor of Zoology, West Virginia University 



The Paraphysis 



The literature of the pineal region of vertebrates is remarkably 

 extensive. A considerable portion of this literature deals with the 

 much-debated relation of the epiphysis to the pineal eye or parietal 

 organ. It is not the purpose of this paper to enter into that discus- 

 sion, for the simple reason that these structures are not present in 

 the alligator. 



O. Hertwig (22)* says that, except in Amphioxus, the pineal 

 gland is not wanting in vertebrates; and Wiedersheim (54) says: 

 " The pineal apparatus consists of the epiphysis or pineal organ 

 proper, which persists in a more or less rudimentary condition in all 

 vertebrates, and a more anterior outgrowth which may be called the 

 parietal organ." 



It is not surprising, then, that various authors should have de- 

 scribed the similarly situated structure in the alligator as the 

 epiphysis. 



Parker and Haswell, in their " Text-book of Zoology," figure 947 

 (from Wiedersheim), show, in a dorsal view of the brain of the 

 alligator, a structure which they call the epiphysis. 



C. L. Herrick (20) mentioned, though he did not describe in 

 detail, the epiphysis of the brain of the alligator. 



The present writer (42), in his previous paper dealing with the 



^ Tlie present paper is one of the results of special researches in continua- 

 tion of my paper on " The Development of the American Alligator," pub- 

 lished in 1908 in Smithsonian Miscellaneous Collections, Vol. 51, 66 pages 

 and 23 plates, in which there was given a general outline of the whole 

 process of development of the American alligator. There was also published 

 in the same series, Vol. 48, pp. 381-387, an article on " The breeding habits 

 of the Florida alligator." 



"The numeral citations in this paper are to bibliographical references at 

 the end of the paper. 



