46 Journal of Comparative Neurology. 



states that he was "unable to describe their earliest condition 

 or give their subsequent history." The third makes its appear- 

 ance in a 13 mm. larva as an evagination in the roof of the 

 prosencephalon. 



Since our sections of Amia show many interesting and un- 

 described features we have thought that the following notes 

 taken from our manuscript on the organogeny of Amia, might 

 be worthy of special mention. 



Our material was fixed in chrom-osmo-acetic, picro-acetic 

 and corrosive-acetic. Our sections comprise the embryonic 

 and larval stages. They were prepared during the winter of 

 1895 by Mr. Brockett, preparateur of the Cambridge Morpho- 

 logical Laboratory. The senior author wishes here to express 

 his gratitude to Mr. Adam Sedgwick and Dr. Hans Gadow for 

 the many courtesies shown. 



The literature on the epiphysis and paraphysis has been so 

 often compiled that we 'deem no apology necessary for its 

 omission.^ 



In order to obtain an accurate conception of the contour 

 and relation of parts we have made reconstructions after the 

 method described by Born. 



Embryo j-/f. days. 

 The epiphysis invariably appears earlier than the paraphy- 

 sis. We have usually found it present in embryos which ex- 

 tend over about two-thirds of the meridional circumference of 

 the yolk. At this time the blastopore is still widely open. The 

 secondary optic vesicles are invaginated and the lens appears as 

 a thickening of the inner layer of the epiblast. While the 

 epiphysis is generally present at this time we have series of the 

 same stage in which there is no trace of it, and even in later 

 stages when the blastopore is completely closed and the tail free 



' A complete bibliography has been published by the junior author in the 

 Proc. Indiana Acad. Sci. 1897. The reader is also referred to the very excellent 

 abstracts of the principal papers given by Sorensen in ih^/ourn. Comp. Neurol. 

 1894, pp. 12-73. 



