Plate 3. 



1-11. Chaetodiadema pallidum A. Ag. and CI. 



1-11. Cystacanths, from the abactinal side of the amubulacral and iuterambulacral plates 

 round the summit of a specimen 65 mm. in diameter. 



1. Front view of a somewhat contracted double cyst, 1 mm. 



2. Single cyst, 1.30 mm. magnification of the drawing reduced one half. 



3. Expanded, showing the pavement of epithelial cells and the two pores, 0.73 mm. 



4. Shows a line of glands, 0.61 mm. 



6. Cystacanth with epithelial cells, 0.66 mm. 



6. Profile, showing a string of glands, 0.60 mm. 



7. Front view with pores, 0.53 mm. 



8. Cystacanths similar in form to fig. 7, 0.56 mm. 



9. Profile of a cystacanth, 0.73 mm. 



10. Younger stage, 0.55 mm. 



11. Similar to fig. 10 with large pores, 0.36 mm. 



The figures are equally magnified except 2 ; measurements give the natural size of the 

 cyst with its spine. 



" Albatross " Ex. 1902. Station 4104. 



