EXPLANATION OF THE LETTERS USED IN THE PLATES. 



The following letters have been employed both in the Enopla and Anopla to designate 

 similar structures : — 



a. Proboscis. 



/. Superior ganglionic commissure. 



g. Inferior do. do. 



j. (Esophageal region. 

 f. Digestive canal proper. 



k. General stroma of the snout. 

 m. Cephalic sac. 

 in! . Duct of do. 



n. Great lateral nerve. 



o. Proboscidian sheath. 

 ov. Ovaries, ova, or their indications. 

 p. Dorsal blood-vessel. 



r. Lateral do. 

 w. Mouth. 



z. Anus. 



\p. Muscular ribbon of proboscis. 



Letters confined to the Enopla. 



ac. Reflection of the proboscis in front of the ganglia. 



b. Epidermis. 



ab. Channel in the snout for the proboscis. 



c. Cutis. 



d. Circular muscular coat. 



e. Longitudinal do. 



h. Superior lobe of the ganglion. 



i. Inferior do. do. 



I. Cephalic blood-vessel. 



q. Anastomotic do. 



a. First region of the proboscis. 



b. Second do. do. 



c. Third do. do. 



