1904.] NATURAL SCIENCES OF PHILADELPHIA. 179 



Fig. 19. — Vermilia pluriannulata. An abdominal uncinus, X 600. 



Fig. 20. — Pomatoceros auritubis. An uncinus from the middle abdominal 



region, showing also the outlines of the front and back faces of the 



large gouge-shaped tooth, X 600. 



Plate XII, Figs. 21 to 25. — Vermilia ctenophora. 



Figs. 21, 21a. — Dorsal and lateral views respectively of operculum, X S. 



Fig. 22. — An average limbate seta from VI, X 250. 



Fig. 23. — The smallest and most curved seta from an abdominal pair, X 440. 



Fig. 24. — Uncinus from V, X 440. 



Fig. 25. — An uncinus from the middle abdominal region, X 440. 



Figs. 26 to 32. — Vermilia pluriannulata. 



Figs. 26, 27, and 28. — Dorsal, ventral and lateral views respectively of the 

 operculum, X 13. 



Figs. 29 and 30. — Long and short slender limbate setse from VI, X 250. 



Fig. 31. — The middle seta of the three on somite XXX, X 440. 



Fig. 32. — An uncinus from V, X 440. 



Figs. 33 to 37.- — Pomatoceros auritubis. 



Figs. 33, 34, 35. — Dorsal, ventral and lateral views respectively of the oper- 

 culum, X 8. 



Fig. 36.— Middle abdominal seta, X 440. 



Fig. 37.— Uncinus from IV, X 440. 



Fig. 38. — Protula geniculata. Seta from middle abdominal region, X 250. 



Fig. 39. — Sabella japonica. Uncinus from dorsal part of VI, X 360. 



Pig. 40. — Sabella japonica. Uncinus from ventral portion of a middle ab- 

 dominal uncinus, X 250. 



Fig. 41. — Potamella acuminata. Uncinus from VI, X 360. 



Fig. 42. — Hypsicomus lyra. Uncinus from VI, X 360. 



Fig. 43. — Euchone alicaudata. Uncinus from XXI, X 360. 



Fig. 44. — Laonome tridentata. Uncinus from XVI, X 360. 



Fig. 45. — Vermilia pluriannulata. End of a capillary caudal seta represent- 

 ing about \ of the exposed part, X 250. 



