1895.] NATURAL SCIENCES OF PHILADELPHIA. 345 



Description of Plate XIII. 



All figures are magnified 112 diameters. 



Figs. 1-3. Spermathecse of Fridericia agricola; 1, in optical 

 section, showing at s a bundle of spermatozoa projecting into the 

 oesophageal lumen; 2, a view of the base of the saccular region, and 

 3, the entire organ of a specimen of the variety mentioned in 

 the text. 



Figs. 4 and 5. Spermathectie of two individuals of F. long a in 

 lateral and basal views. 



Fig. 6. Salivary gland of F. longa. 



Fig. 7. " " " F. agricola. 



Fig. 8. " " " F. alba. 



Fig. 9. " " " F. parva. 



Fig. 10. Spermatheca of F. parva. 



Fig. 11. " " F. alba. 



