30 Journal of Comparative Neurology. 



II. Reptilia. (n) The development of the epiphysis in 

 reptiles is similar to that in amphibians. 



(12) A more thorough investigation of the part of the 

 epiphysis constricted off brought out the following: The struc- 

 ture in question lies between the meninges; it has the form of a 

 round, more or less compressed, independent vesicle, and ex- 

 hibits a cellular structure. The wall next to the parietal fora- 

 men is thickened into the form of a lense while the basal wall 

 is pigmented on the interior. 



(13) In Anguis fragilis the part of the epiphysis constrict- 

 ed off is also originally a vesicle, in which we can, however, later 

 show a higher differentiation. The basal wall is composed of 

 several layers, in the following order passing from within out- 

 ward. First, a layer of very long, narrow cylindrical cells whose 

 basal portion is completely imbedded in a deep black pigment. 

 The part of these cells toward the cavity of the vesicle is per- 

 fectly clear and exhibits forms which by their refractive property 

 remind one of the rod layer of the retina ; their structure is not 

 fully known. Then follows a layer of cells with large round 

 nuclei which are imbedded in a fine granulated substance ; and 

 next to this at the periphery a layer of cells likewise bearing 

 large nuclei that lie in two rows on the upper side. The entire 

 lower wall becomes thinner as it arches upward and the continu- 

 ity with the upper wall is completely interrupted, the latter is 

 thickened into the form of a lens and consists of long, narrow, 

 cylindrical cells, resembling more or less the embryonic lens. 

 On this account the entire portion constricted from the epiphysis 

 in Anguis fragilis resembles somewhat the eye of the more highly 

 developed invertebrates, such as is known, e. g. , in Cephalo- 

 poda, Pteropoda, and Heteropoda. 



(14) The epiphysis in Anguis fragilis is very much twisted 

 and its epithelium is ciliated. 



(15) The fact that a part of the epiphysis which is con- 

 stricted off and lies outside the cranium under the pia mater in 

 Amphibia (Anura) comes to lie outside the brain below the par- 

 ietal foramen in Sauria (Lacerta and Anguis) establishes, as the 

 ontogenetic development has already shown, the homology of 



