PLATE XX 



FIG. i. AmpJnporus crnentatus Verrill. Optical section of stylet apparatus 

 of proboscis after extrusion. To the right of the basis is seen duct leading for- 

 ward from middle to anterior proboscis chamber. X 22 - 



FIGS. 2-5. A. cruentatus. Outlines of central stylets and bases, showing varia- 

 tion in size and form in different individuals. X 22 - 



FIG. 6. A. cruentatus. Outline of head, showing comparative size and posi- 

 tion of ocelli. X 3- 



FIG. 7. Tetrastcmma rcticulatum Coe. Optical section of stylet apparatus 

 of proboscis. X 22 - 



FIGS. 8, 9. T. reticulatum. Outlines of central stylets and bases in two indi- 

 viduals. X 22 - 



FIGS. 10, ii. Nemertopsis gracilis Coe. Outlines of bases of central stylets 

 in two individuals. X 3- 



FIGS. 12, 13. Tetrastcmma quadrilineatum Coe. Outlines of central stylets 

 and bases in two individuals. X 43- 



FIGS. 14, 15. Parancmcrtes pcregrina Coe. Outlines of central stylets and 

 bases, showing the peculiar braided appearance of stylet. Both central and ac- 

 cessory stylets present this peculiarity. The braided appearance is probably due 

 to a deep spiral fluting, the translucence of the stylets allowing the flutings of 

 both upper and lower surfaces to appear as if actually crossing. X 3- 



FIG. 16. Tctrastemma nigrifrons Coe. Outline of central stylet and basis 

 (see pi. xxi, figs. 15-23). X 22 - 



(216) 



