^4 



pep. proboscis epithelium. 



Pil. pigment layer of eye. 



p}i. proboscis nerve. 



ps. proboscis sheath. 



/•(/. rhynchodaeum. 



rhc. rhynchocoelom. 



rhce. rhynchocoelomic epith- 

 elium. 



adij. superior lobe of dorsal 



ganglion. 

 ss. lateral nerve. 

 vc. ventral commissure. 

 X'ep. epithelium of blood vesse 1 

 vg. ventral ganglion. 



Fig-. 

 Fig. 

 Fig. 



Fig. 



Fig. 

 Fig. 



Plate L 



1. Transverse seotinn through the lip of the liead. 



X 60. 



2. Transverse section taken between brain and tip 



of snout. X 45. 



3. Transverse section through hinder part of brain, 



where the anterior gland of the cerebral organ 

 opens near the end of the head slits. x 60. 



4. Transverse section through dorsal commissure 



before the two limbs of the cephalic vascular 

 loops have fused ventral to the proboscis 

 sheath. x 45. 



5. Transverse section through brain at a level 



between 4 and 8. x 45. 



6. Transverse section through level of cerebral 



organ, buccal vascular commissuje and 

 oesophageal nervous commissure. 



Plate II. 



I'ig. 1. Transverse section through mouth region. The 

 (esophageal vascular lacunae are just com- 

 mencing. X 45. 



Fig. 2. Transverse section through about the middle of 

 the oesophageal region. x 45, 



