SEMDN (il)^ working on a holothurian, found the two 

 planes in question tc coincide, but his conclusion 

 is based on the supposition that the dorsal mesentery 

 of the adult is the same- as that of the auricularia 

 larva, which supposition BURY has since shown to be 

 in correct 



BURY (3) ; after working on members of all the 

 Croups of echinodermsj concluded that the plane of 

 bilateral symmetry of the larval form coincides. not 

 with the plane dividing the adult form into two sym- 

 metrical halves but ? with the plan? of radial symmetry. 



McBRIDES (£) observation on a star-fish, Asterina 

 gibbesa, led him to adopt about the same view as that 

 of BURY. He found that the plane of radial symmetry 

 of the star makes an angle of 70 °f ( but may, without . 

 error, be considered as 30*) with the frontal plane 

 of the larva. This is equivalent, to saying that the 

 . - - of radial symmetry of the star is parallel with 

 the sagittal or plane of bilateral symmtfcfcy of the 

 larva, and is also reducible to the statement that 

 the planes of bilateral symmetry of the larva and : 

 adult arc at right angles to ens another. Thus right 

 and left in the larva becomes aboral and oral in the 

 adult . 



THe difference in results arrived at by GOTO 



