CENTRAL NERVOUS M>IKM IN I'l.ANAKIX. 



49 



normal than that of Fig. 12. Two nerves, one from each portion 

 of the ganglionic mass, pass to the optic cup. 



He-re, as in the preceding case, the eye is situated near the 

 extreme anterior end of the ganglionic re-ion instead of a con- 

 -iderable distance posterior to it as in normal forms. Posterior 

 i" the eye tin- torm of the ganglionic mas- i-ontinues murh the 

 -ame a- in I i_ 18 to about the posterior end of the ne\\ iiue. 

 uliere the He lit and left portions become more distinetly -epa- 

 r.iied \\itli .1 commissure between them and then pa into the 

 tuo ner\ e e..rds. 



In general form the nervous system is much le abnormal in 

 i hi- i hati in the preceding case. The chief difference- from the 

 norm are the anterior position of the eye on the ean-lionic ma-- 

 and the partial !u-ion of the two ganglia for a considerable di-- 

 tanee |i-ierior to the eye. 



v \- indicated in Fig. i<), this case shows a someu hat extreme 



2O 



21 







FlGS. IQ 22. 



lorm of teratomorphism. The two auricle- are tn-ed at the lip 

 of the head, though the sensory areas are in large part separate. 

 A -ingle median eve is present as in the preceding < 



I ig. 20 sho\\ - a t ransverse section < >t the IHT\ < m- -\ -tern .it the 

 level where the in t \ e- to the front of the head ari-e: rlii- is about 



