Studies on the Development of Larvai Nephridia. 513 



Fig. n. Ph. hippoerepia, Lateral view of a young larva showing the trunk 

 coelom and nephridia. 



Fig. 18. Ph. hippocrepia, Same view of a larva slightly older then the last. 



Fig. 19 — 24. Ph. branchiata, A series of consecutive sections through a young 

 larva with two pairs of tentacles. 



Fig. 25. Ph. psammophila, Nephridium early stage. 



Fig. 26. Ph. psammophila, Lateral view of a whole preparation. 



Fig. 27. Ph. j)sammophila, Dorsal view of the previous. 



Fig. 28. Ph. hi'ppocrrpia, Nephridia 4S hours after the larvae have left the ten- 

 tacles of the adult. 



Fig. 29. Ph. psammophila, Nephridium early stage. 



Piate 32. 



Fig. 30. Ph. hippocrepia, Sagittal section of a young larva from the tentacles 



of the adult. 

 Fig. 31. Ph. hippocrepia, Sagittal section slightly later stage. 

 Fig. 32. Ph. hippocrepia, Coronai section slightly oblique. 

 Fig. 33. Ph. hippocrepia. Median section of a larva with two pairs of tentacles. 

 Fig. 34. Ph. hippocrepia, Median section. 



Fig. 35. Ph. branchiata, Transverse section showing tentacles and body cavity. 

 Fig. 3ö. Ph. Iiippocrepia , Median section of the same larva as that shown in 



Fig. 34, this section being more median. 

 Fig. 37. Pli. psammophila, Coronai section showing anal pit. 

 Fig. 38. Ph. iiippocrepia, Similar section to that of Fig. 37. 

 Fig. 39. Ph. hippocrepia , Section through the same larva as that shown in 



Fig. 33, this section being taken through a plane more median to that 



of the former. 

 Fig. 40. Ph. branchiata, Transverse section through the coUar region. 

 Fig. 41. Ph. hippocrepia, Section showing the lateral portion of the coelom. 

 Fig. 42. Ph. branchiata, Transverse section. 

 Fig. 43. Ph. hippocrepia, Transverse section through the posterior region of 



young larva, showing the nephridial canals, tentacles and the preorai 



lobe folded back on the trunk. 

 Fig. 44. Ph. iiip)pocrepia, Section slightly lateral to the median line. 

 Fig. 45. Pli. hijipocrepia, Section showing the nephridial pit, part of the trunk 



coelom, and one of the nephridial canals. 

 Fig. 46 and 47. Ph. hippocrepia, Two consecutive sections through a larva just 



free from the tentacles of the adiilt. 

 Fig. 48. Ph. branchiata, Transverse section. 

 l'ig. 49. Ph. hippocrepia. Dorsal view. 

 Fig. 50. Ph. hippocrepia. Oblique section through a young larva of about the 



same age as that represented in Fig. 49. 

 Fig. 51 and 52. Ph. branchiata, Section through one of the nephridial canals, 



and the blood-corpuscle mass of the fully formed Actinotrocha. 



Fig. 51 shows the solenocytes and the branched funnel ends of one 



of the nephridia. 

 Fig. 53. Ph. hippocrepia. Whole preparation seen from the dorsal surface. A 



younger stage tbau that shown in Fig. 49. 

 Fig. 54. Ph. hippocrepia. Dorsal view of a whole preparation. 



