248 MILDRED HOGE RICHARDS AND ESTHER V. FURROW. 



duplex, representing both median and inner. Sometimes one of 

 the ganglia, as in Fig. 3, will show the double lens-like structure 



best seen in transverse sections. In Fig. 4 each of the two 

 ganglia show this double nature, similar to that of the normal eye. 

 The contraction in the two inner ganglia in part explains the 

 great reduction in the size of the eyeless head. 



We have never failed in the many heads studied to identify in the 

 totally eyeless half both median and inner ganglia. Plate III., 

 Fig. 3, shows no eye on the left side, but here the section does not 

 go through the optic tract. However, both the median and inner 

 ganglia appear in other sections of this head. Fig. 5 shows also a 

 totally eyeless condition on the left side and there is no trace of the 

 outer ganglion. The section goes through the whole optic tract of 

 this side showing clearly both median and inner ganglia, each hav- 

 ing a double lens-like appearance as on the opposite side, where 

 the eye is present. The- left side of the head is correspond in jjy 

 smaller than the right giving it a twisted appearance, and tln-iv 



