M»>i;niiM;i:.\i:sis nv iiri': 



^■f. 



t.clr^x. 



It'-- 



t.c.cL. 



n.a.t. 



EXPLANATION OF FIGURES 



23 Median view of the region around the foramen interventriculare in an 

 embryo of Chrysemys marginata having a carapace 8.6 mm. in length. Embryo 

 5 b. X 100. In order to show the fissura chorioidea it was necessary to remove 

 the paraphysis and represent the fissure slightly higher than it really is. 



536 



