304 J- Playfair McMuerich, 



Fig. 15. View of the distal ijortion of tbe individual represented in 

 Fig. IIA, from the opposite side, sbowing the absence of tentacles. 



Fig. 16. Paractis nivea (Lesson). 1:1. 



Fig. 17. Transverse section of the sphincter of P. nivea. 



Fig. 18. Transverse section of a mesentery of tbe first cycle of P. 

 nivea, tbe section being takeu in the upper expanded portion of tbe column. 



Fig. 19. Transverse section of a first cycle mesentery of P. nivea, 

 taken in the lower part of tbe column. 



Fig. 20. Paractis ignota n. sp. 1:1. 



Fig. 21. Transverse section of tbe sphincter of P. ignota. 



Fig. 22. Transverse section of a fii'st cycle mesentery of P. ignota, 

 taken below the level of the stomatodaeum. 



Fig. 23. Paractis iemiicollis n. sp. 1:1. 



Fig. 24. View of distal portion of tbe column of P. temiicoUis. 



Fig. 25. Transverse section of the sphincter of P. tenuicoUis. 



Fig. 26. Transverse section througb a first cycle mesentery of P. 

 iennieollis, taken below tbe level of tbe stomatodaeum. 



Fig. 27. Pycnanihus Uneolatus (Mc Murrich). 1:1. 



Fig. 28. Transverse section througb the sphincter of P. Uneolatus. 



Fig. 29. Transverse section of a portion of the column of P. Uneo- 

 latus with mesenteries of the first, third and fourth cycles ; tbe section is 

 taken below the level of the stomatodaeum. 



Fig. 30. Äctinostola chilensis n. sp. 1:1. 



Fig. 31. Tangential section of the disc of A. chilensis. 



Plate 16. 



Fig. 32. Transverse section througb tbe sphincter of A. chilensis. 



Fig. 33. Transverse section througb a portion of the column wall 

 of A. chilensis, sbowing mesenteries of tbe 1., 3., 4. and 5. cycles. 



Fig. 34. Boloceropsis platei 7i. sp. 1:1. 



Fig. 35. Section througb tbe raargin and tbe base of a tentacle 

 of B. platei. 



Fig. 36. Phymactis clematis (Drayton) Carlgren. 1 : 1. 



Fig. 37 and 38. Surface views of a portion of the column of two 

 individuals of P. clematis sbowing the form of tbe tubercles. 



Fig. 39. Transverse section througb the margin of P. clematis sbow- 

 ing tbe sphincter and an acrorbagus. 



Fig. 40. Transverse section througb a portion of a tentacle of 

 P. clematis. 



Fig. 41. Tangential section of a portion of tbe disc of P. clematis. 



Fig. 42. Transverse sections of a second cycle mesentery of P. cle- 

 matis showing {a) the longitudinal and (/>) tbe parieto-basilar muscle. 



