3i8 



MEAD. 



EXPLANATION OF PLATE XV. 



Fig. 65. 



Fig. 66. 



Fig. 67. 



Fig. 68. 



Fig. 69. 

 rosette." 



Fig. 70. 



Fig. 71. 



Fig. 72. 

 correspond 



Fig. 73. 



Fig. 74. 



Fig. 75. 

 Fig. 76. 



Clymenella torquata Verrill. 



From animal pole (nearly) : 2-cell stage. 



Same view : 4-cell stage. 



From vegetative pole : 8-cell stage. 



i6-cell stage from animal pole : from life. 



Same view : thirty-two to sixty-four cells ; formation of " apical 



Same view : primary prototroch complete 

 Same view : rosette cells dividing. 



Same view : two of the rosette cells have divided ; gl.l. and gl.rt. 

 to mucous gland cells in Amphitrite, "head-kidneys " in Ne->eis 

 Lower hemisphere : 32-cell stage; from life. 

 Same view: 32 to 64-cell stage; formation of mesoderm cell 



Right side : same stage. 



Left side : about the same stage. 



