524 C. JUDSON HERR1CK 



EXPLANATION OF FIGURES 



42. Transverse section through the middle of the cerebral hemisphere of La- 

 acert muralis (?) embryo of 7.6 mm. (measured across tiie greatest diameter of 

 the coil as it lies in the egg). Haivard Embryological Collection, series 1601, 

 section 121. X 24. 



43, 44, 45. Three transverse sections through the cerebral hemisphere of a 

 16.7 mm. embryo of Chrysemys marginata. Harvard Embryological CoUection, 

 series 1092. X 28. 



43. Section 175, through the middle of the septum. 



44. Section 190, taken 150 micra farther caudad than the last, showing an un- 

 differentiated remnant of the primoidium hippocampi vent rally of the cortex 

 hippocampi. 



45. Section 195, taken 50 micra farther caudad, immediately rostral to the inter- 

 ventricular foramen, illustrating the septum ependymale. 



46. Section taken in the same plane as fig. 45 through an older embryo of Chrys- 

 emys marginata of 27 mm. Harvard Embryological Collection, series 1096, sec- 

 tion 168. X 36. 



