4fi 



Fig. 55. Horizontal section of the central capsule and 

 the chambered organ, at ahont the level of the 

 line * * * in fig. 59. x 40. 



Fig. 56. Horizontal section of the pentagonal com- 

 missure, at about the level of the line t in 

 fig. 59. X 40. 



Fig. 57. Horizontal section of the central capsule and 

 the chambered organ, at about the level of the 

 line * * in fig. 59. x 40. 



Fig. 58. Transverse (a) and longitudinal (b) sections of 

 a cirrus cord and the included cirrus vessel. 

 X 350. 



Fig. 59. Portion of a sagittal section of the disc, showing 

 the central capsule, radial and cirrus cords, 

 chambered organ and axial organ. x 40. 



Fig. 60. Horizontal section of the base of an arm passing 

 through the first four secundibrachials, and 

 showing the double roots of the two first 

 pinnular branches of brachial nerve cord, x 30. 



Plate YII. 



Fig. 61. Horizontal longitudinal section of a pinnule, 

 with a ripe testis showing the lateral papilli- 

 forra projection through which the sperm- 

 atozoa would eventually escape. x 56. 



Fig. 62. Transverse section of a pinnule, with a nearly 

 ripe ovary. x 40. 



Fig. 63. Horizontal longitudinal section of an embryo, 

 fifty-seven hours old. After Seeliger, from 

 Lang. 



Fig. 64. Posterior end of an embryo, sixty hours old, 

 seen from the right side. After Seeliger, 

 from Lang. 



