100 



The basal portions of the evaginations taken together constitute 

 the perihaemal ring- canal ; the distal portions become produced each 

 into two tongues which commence to penetrate the rays and form the 

 radial perihaemal canals. The two canals lying side by side found 

 in each ray originate from the evaginations situated in the two adja- 

 cent interradii. 



On the other hand Mr. Goto asserts that: — 



( 1 ) The rudiments of the aboral surface of the adult called collectively 

 the aboral disc make their appearance on the right side and posterior 

 aspect of the larva in both Asterias pallida and in Asterina gibbosa. In 

 the former case the aboral disc becomes displaced until it occupies 

 the posterior pole of the larva; in Asterina gibbosa the same thing 

 really occurs but is masked owing to the circumstance that the prae- 

 oral lobe becomes bent to the right side in consequence of the une- 

 qual rate at which the atrophy of its two sides proceeds. As a result in 

 Asterina gibbosa the aboral disc remains throughout the metamor- 

 phosis apparently obliquely inclined to the sagittal plane of the larva, 

 whereas in Asterias pallida this plane eventually cuts the disc at 

 right angles, so that the assertion may be made that the planes of 

 symmetry of the larva and adult are identical. 



(2) In the young larva of both Asterias pallida and Asterina gib- 

 bosa the coelom (or enterocoele) consists of two cavities communicat- 

 ing widely with one another in the prae-oral lobe. From the left 

 cavity a posterior division, the left posterior enterocoele, is completely 

 interina gibbosa) or incompletely {Asterias pallida) divided off. 

 The original ventral mesentery separating the right and left coelomic 

 sacs becomes partly absorbed and replaced by a new oblique mesen- 

 tery which cuts off entirely a portion of the right sac, called by Goto 

 the " Epigastric coelom" since it gives rise to the coelom lying above 

 the stomach in the adult. In the case of Asterina gibbosa Goto has 

 seen the secondary perforation of the septum on the left side, as de- 

 scribed by me. 



(3) The sac denominated by me the right hydrocoele is stated by 

 Goto to arise from the left coelomic sac, at the level of the madre- 

 poric pore, which he regards as the boundary between the anterior and 

 posterior coelomic sacs. In the case of Asterias pallida he denied that 

 the sac was identical with the closed space found near the madreporite 

 in the adult; this statement he retracts when dealing with Asterina 

 gibbosa, but still asserts that in Asterias pallida the sac opens at a 

 late period into the axial sinus. According to him the origin of this 

 sac from the left coelomic sac negatives the idea that it can be a right 

 hydrocoele. 



