GOTO. — EMBRYOLOGY OF STARFISH. 333 



XVII. 



CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF 



THE MUSEUM OF COMPARATIVE Z(JOLOGY AT HARVARD 



COLLEGE, UNDER THE DIRECTION OF E. L. MARK, LXIV. 



PRELIMINARY NOTES ON THE EMBRYOLOGY OF 

 THE STARFISH (ASTERIAS PALLIDA). 



By Seitaro Goto. 



PreBented by E. L. Mark, April 8, 1896. 



In this preliminary notice I propose to give a brief account of the 

 principal results of the study which I have been carrying on during 

 the past winter. Since I began my study, two papers in the " Quar- 

 terly Journal of Microscopical Science," covering the same ground in 

 other species, have come to ray notice, one by Bury, and the other by 

 MacBride. But as the results of these observers are at variance on 

 some important points, it will, I believe, not be without interest to 

 publish my own, which, it will be seen, are mostly, but not altogether, 

 confifmations of those of MacBride. 



The material was collected last summer in Mr. Agassiz's Laboratory 

 at Newport, R. I., where I was enabled to work for several weeks 

 through the courtesy of the owner, to whom my best thanks are due. 

 It will be observed that I have studied the same species as that on 

 which Mr, Agassiz himself worked about thirty years ago, — a spe- 

 cies which in the course of its development passes through typical 

 Bipinnaria and Brachiolaria stages. 



(1) A few words as to the orientation of the body. In the Bra- 

 chiolaria stage the sagittal plane of the body passes through the dorsal 

 Brachiolaria arm, and is at right angles to the line joining the tips of the 

 other two arms. It also passes through the anus and the middle of the 

 mouth. In later stages, as metamorphosis approaches more and more 

 its end, the anus shifts its position considerably, and the sagittal plane 

 can be determined externally only by means of the Brachiolaria arms. 

 I find the plane determined by this means constant for all practical 

 purposes ; that is to say, it bisects the stomach as well as the body as 

 a whole, and passes through both the dorsal pore and the point where 



