EXPLANATION OF PLATE XX. 



Heterakis macronis, sp. iiov. 



Fig. 25. — (f . Transverse section middle of body. X 433^ 

 (Series i, slide i). Shows the body of the 

 ventral gland. 



,, 26. — a'. Transverse section behind fig. 25. X 433^. (Series 

 I, slide 2/4/). Shows the processes of the ven- 

 tral gland and the ascending (t. i.) and des- 

 cending (t. 2) limbs of the testis. 



27. — cf . Transverse section behind fig. 26. X 433^. (Series 

 I, slide 2, end). Shows the processes of the 

 ventral gland coming into close relationship 

 with the lateral lines. 



J, 28. — cf . Transverse section behind fig. 27. X 433^. (Series 

 I, slide 3/2/). Shows the processes of the ven- 

 tral gland near their termination, in the sub- 

 stance of the lateral lines. 



,, 28a. — cf. Transverse section through the lateral line behind 

 fig. 28. X1500. (Series i, slide 2/3/ end). 

 Shows the end of a ventral gland process, with 

 its canaliculus which possesses a well-marked 

 wall. 



,, 29. — cf . Transverse section behind fig. 28. X 433^^. (Series 

 I, slide 3/4/ mid). Shows a canaliculus in the 

 lateral line. 



,, 30. — cf. Transverse section behind fig. 29. X 433^. (Series 

 I, slide 4/2/). At the transition from testis to 

 seminal vesicle. 



,, 31. — cf> . Transverse section behind fig. 30. X 433^. (Series 

 I, slide 4/4/). Through the seminal vesicle. 



,, 32. — cf . Transverse section behind fig. 31. X 433^. (Series 

 I, slide 5/2/1 ). Through the ductus ejacula- 

 torius. 



„ 33. — cf . Transverse section behind fig. 32. X 1000. (Series 

 I, slide 5/3/). Shows canaliculi in the lateral 

 line and the anogenital glands. 



,, 34- — cr' • Transverse section through tail behind fig. 33, and 

 slightly in front of the anogenital aperture. 

 X 433i- Shows the base of one spicule^ the 

 anogenital glands with their ducts, the cushion 

 of the bursa. (Series i, slide 6). 



