PLATE XIX. 



Fig. 

 1 Enlarged view of the anterior region of Lineus gesserensis, as a transparent object. 



2. Anterior portion of Lineus sanguineus, g, peculiar incurvation of the wall of the ali- 



mentary canal, marking the boundary between the oesophageal and the succeeding division 

 of the digestive apparatus. X 90 diam. 



3. Anterior portion of Lineus lacteus. X 90 diam. 



4. Portion of the middle region of L. gesserensis, representing the arrangement of the vessels in 



the living animal. Considerably enlarged. 



5. Arrangement of the vessels at the posterior extremity of the same species. Similarly 



magnified. 



6. Posterior portion of a specimen of the same species having an unusually distinct anus 



(probably from partial repair after injury). a, mass of granular and cellular debris 

 revolving in the direction of the arrow by aid of the cilia of the digestive cavity ; b, anus. 

 X 210 diam. 



7. Transverse section of the proboscis of Borlasia Mizabethce. X 210 diam. 



8. Transverse section of the proboscis of Micrura fusca. X 350 diam. 



9. Highly magnified view of the anterior end of Cephalothrix linearis, 6, b, bridles of the sheath 



for the proboscis. 



10. Gregariniform parasite from the digestive canal of Lineus lacteus. X 350 diam. 



11. Outline of one of the same parasites after prolonged immersion in water. 



