Fig. 43. Radial section of a rhopaliiim in the stage of 

 Fig. 18. Zeiss H oc.2. 



Fig. -'i4. Radial section of a rhopalium in about the stage 

 of Fig. 19. Zeiss H oc.2. 



Fig. 45. A similar section throtigh the degenerated rem- 

 nant of an interradial tentacle from the same specimen. 



Fig. 46. A somev/hat obliquely transverse section of a 

 fully developed scyphistoma showing the relations of the sep- 

 tal muscles to the depressions in the circumoral disk. Zeiss. 

 DD. 0C.4. 



Fig. 47. Section in the plane of an interradius from a 

 similar larva. Zeiss. C oc.2. 



Fig. 48. Part of the opposite side of a similar section 

 of the same series, more highly magnified to show the histolo- 

 gy of the parts. Zeiss. H oc.2. 



Fig. 49. Radial section showing the course of a septal 

 muscle in a strobila. X 313. 



Fig. 50. A similar section from an older specimen. X 

 Zeiss DD oc.2. X point of separation between the t#o disks. 



Fig. 51. A r.edian verticle section of a young medusa that 

 has very recently become free X is opposite the opening that 

 formerly lead into the lower disk of the strobila. Zeiss DD 

 oc.2. 



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