398 Dr. F. A, Bather — Studies in Edrioasteroidea. 



Ill 



II 



madreporite 

 closure of 

 brachiolarian 

 notch 



1 anus, v 



stalk, 

 hydrocoel-closure 

 Fig. 1. 



hydropore 



rotation of 

 III hydrocircus 



IV 



-. mouth 

 amis 

 V 

 sucker 



Fig. 2. 



Ill 



covering 

 plates 



II 



inler- 



TadicuL 



plates 



anus 



Fig. 



flooring 

 ...plates 

 rruntth 



IV 



W^' "water- pore 

 "pores in, 

 food-groove 



Fig. 3. 



IV 



mouth 

 hydropore 

 - anus 



Fig. 4. 



1. — Diagram to illustrate MacBride and GemmilPs numbering of the rays 

 in Asterias. The view is from the oral side. The position of the anus is 

 that occupied by it in the adult, but it opens on the apical side. 

 Fig. 2. — Diagram of Asterias at the beginning of metamorphosis, based on the 

 figures and description of Gemmill. The view is from the oral side, on 

 which side the anus opens at this stage. The numbers I-V correspond 

 with II, III, IV, V, I in Fig. 1. Hydrocoel pouches are numbered 1-5. 



FlG. 3. — Oral face of Edrioaster bigsbyi. The numbers I-V correspond with 

 those in Figs. 2 and 4, but not with those in Fig. 1. 



FlG. 4. — Diagram to show the supposed relations of water-vascular system and 

 gut in young Edrioaster. The view is from the oral side. The numbers 

 I-V correspond with those in Fig. 2. The ends of the hydrocoel pouches 

 1, 2, 3, 4 enter rays 5, 1, 2, 3 respectively, and in this regard make those 

 rays correspond with rays I, II, III, IV of Fig. 1. The hydropore leads 

 into the stone-canal, and probably into a genital duct. 



