STUDIES ON THE PROTOCHORDATA. 317 



Studies on the Protochordata. 



By 



Arthur IVilley, B.ScXond., 



Columbia College, New "York. 



With Plates XXX & XXXL 



I. 



On the Origin of the Branchial Stigmata, Praeoral Lobe, En- 

 dostyle, Atrial Cavities, &c., in Ciona intestinalis, Linn., 

 with Remarks on Clavelina lepadiformis. 



In continuation of some work on the development of Am- 

 phioxus, which, thanks to Professor Lankester, I had been 

 enabled to do, I undertook — at his recommendation, and with 

 the assistance of a grant from the Royal Society — a course of 

 study on Ascidian development, with a view to coming to 

 some definite conclusion as to the relations between the Uro- 

 chorda and the Cephalochorda, and to control by actual in- 

 vestigation the general conclusions expressed in my paper on 

 the " Later Larval Development of Amphioxus," which, in so 

 far as they related to the Ascidians, were mainly based on the 

 results arrived at by Ed. van Beneden and Charles Julin 

 in their ' Recherches sur la Morphologic des Tuniciers/ 



I accordingly spent six weeks at the Marine Biological La- 

 boratory at Plymouth, in the long vacation of 1891, followed 

 by ten months at the Zoological Station of Naples, at both of 

 which institutions I had the privilege of occupying the table 

 of the British Association. 



Having now made personal observations on the development 



