148 ARTHUR WTLLRY. 



occupy a table. I collected the material myself in tlie 

 company of a friend from the piles of a wharf at New 

 Bedford. 



All tlie nepionic stages of Ciona, which I observed at 

 Naples, were reared in jars from artificially fertilised egg's ; 

 those of Molgula manliattensis were collected in the 

 open. I gave tlie gist of my observations on tlie protostig- 

 mata of the latter species in the book entitled ' Amphioxns 

 and the Ancestry of the Vertebrates/ ^ which I prepared for 

 the Columbia University Biological Series, and intended to let 

 that suffice. For various reasons, however, I have come to 

 the conclusion that it would be desirable to furnish further 

 details, and that is the object of the present contribution. 



As previously noted by Kingsley,^ this species is viviparous, 

 in so far that the embryonic development, during which the 

 embryo is surrounded by the follicular membrane, takes place 

 within the peribranchial chamber of the parent. 



In the urodele larva the organ of fixation assumes the 

 form of a hollow lobe at the anterior end of the body, much as 

 in Ciona, where I identified it as a pr^eoral lobe. The main 

 body of the larva is so opaque that the internal structures 

 cannot be made out in any detail without sections. I could 

 not see the buccal and atrial orifices in the larva before 

 fixation ; but after fixation there ajjpeared, in addition to the 

 buccal orifice, a single median atrial siphon. It would be 

 interesting to have it established exactly at what moment the 

 month breaks through, since this crucial event appears to 

 vary in relative time of occurrence in different species. In 

 another Molgulid, Lithonephria eugyranda Giard, Julin^ 

 finds that the mouth is formed long before the hatching of 

 the larva. 



In the larva of M. manliattensis, at the time of fixation, 

 the praeoral lobe elongates as a stolon-like tube, and at the 



> 1894, see pp. 232—233. 



2 J. S. Kingsley, "Some Points in the Development of Molgnla man- 

 liattensis," 'Proc. Boston Soc. Nat. Hist.,' xxi, 1882, pp. 441—451. The 

 account of the segmentation stages was erroneons. 



* Op. cit., see pp. 355-G. 



