Pomona College, Claremoiit, C;ilifi)rni.i 33 



EXPLANATION OF FIGURES 



Figure I. Central nervous system of Pliascolosoma X15. The cord is shown in 

 three separate pieces. The lower ciul of the first or left-hand drawing should join 

 with the second and so on. The central nerve band is shown with the lateral branches 

 of muscle and nerve. The brain is shown attached to the first segment at the left. The 

 pigment spots, cerebral tubes and chief nerves are shown. The brain is drawn from 

 reconstructions made from serial sections. 



Figure 2. Cross section of the nerve cord. .\75. 



Figure 3. Longitudinal section of the nerve cord. X75. 



Figures 4 to 6. Drawings of sections taken through the brain at various levels, 

 only one-half is shown in each case. X75. 



