The Brain of Diemyctylus Viridescens 285 



EPIPHYSIS AND PARAPHYSIS. 



In the roof of the brain two outgrowths from the cavities 

 have been found in embrj'os of all groups, the epiphysis 

 arising from the diencephal between the supra- and postcom- 

 missures, the paraphysis farther cephalad and variously said 

 to belong to the prosen- and diencephal. From a morpholog- 

 ical standpoint theimportance of these organs has been con- 

 sidered great, hence many special articles have been devoted 

 to them. The history and present state of knowledge con- 

 cerning them has recently been discussed by Beraneck (5) and 

 His (27). In brief, the epiphysis is said to develop variously 

 in different groups, becoming the pineal or parietal eye of 

 lizards and lamprey, the conarium of mammals, while in am- 

 phibia it is very degenerate and was first discovered by Gotte 

 (20). The fate of the paraphysis in the adult has been very 

 uncertain. Observations of Hoffmann (28) are very suggestive 

 with reference to the possible relation of the neuropore with 

 the paraphysis. 



Epiphysis. — As seen in the figures the epiphysis of diemyc- 

 tylus like that of other urodeles is insignificant. In embryos 

 it is prominent, in the early larval stages a remnant of its 

 connection with the brain remains (Fig. 68) occuring as usual 

 between the supra- and postcommissures. In the adult this 

 connection has disappeared and its cavity is nearly obliterated. 

 Figure 58 shows a few lacunae in it and the fact that it is in a 

 region of numerous blood vessels. From its caudal end a few 

 fibers pass toward the roof of the mesencephal forming a pic- 

 ture (Fig. 52) which resembles the condition in the frog as 

 shown by Osborn (37). From the degenerate condition it 

 would probably be impossible to determine whether these are 

 nervous or connective tissue elements. 



In the amia as in other ganoids, the epiphysis lies to the 

 left of the meson, owing to the greater development of the 

 right habena (Fig. 97-99). In this specimen figured, which 

 is nearly adult, the stalk can be traced to its union with the 

 brain. This union is by a tortuous path owing to the crowd- 

 ing of the habense. 



