﻿Dec,, 1857.] 



ELLIOTT SOCIETY. 



261 



rowing as it proceeded inwardly, and not very far from the oral 

 extremity appeared to form another circular aperture, narrower 

 than the external mouth. 



Though these specimens did not complete their growth, and 

 thereby demonstrate their specific relations, yet I think that the 

 main facts of their condition at this stage, with the exception of 

 the absence of tentacula, are in accordance with the facts recorded 

 of the development of Bolina. They are these. That the em. 

 bryo very early assumes the Beroid form. That the central por- 

 tion of the circulatory system above the digestive cavity is, at first, 

 lacunar in form. That the zone wherein this central portion en- 

 counters the extreme surface of the animal, is the zone whence 

 the development of the external surface and the structures con- 

 nected with it begins. That this development is first directed up- 

 wards towards the sense-capsule at the superior pole of the body, 

 and that it is not until later that it begins to direct itself to the 

 lower pole. That the gastric tubes precede the superficial tubes 

 in development — that all the latter precede the ambulacra more or 

 less in their progress downward — and that of the four superficial 

 tubes belonging to each side of the bod)'-, the two which approach 

 the angle of the oral cleft, precede in their downward progress 

 the other two which are interposed between them. 



These facts agree with those obtained by Joh. Muller, at 

 Trieste, and by Kolliker, at Messina. , In fact, the latter author 

 (Wissenchaftliche Zoologie, vol. iv. p. 318,) has described a 

 younger Beroid than any which I have seen ; for he says, that 

 while it possessed a mouth, digestive cavity, sense-capsule, and 

 eight (paired) rows of ciliary blades, it was entirely without any 

 trace of the circulatory system, with the exception of the single 

 ascending tube, which proceeds from the summit of the digestive 

 cavity to the sense-capsule, at the superior pole. That it wanted 

 tentacula, does not show necessarily that it w T as extremely young, 

 for it is probable, from my observations, that Beroe never has any 

 trace of tentacula. 



It is also probable, that these observations will considerably re- 

 duce the number of species and genera of Ctenophora, where these 

 have been created for minute specimens. It is, I think, probable, 

 that both the species of Eschscholtzia, described by Kolliker, as 

 well as his genus Owenia, are only young stages of perhaps 

 known adult Ctenophora. The Cydippe qvadricodstata of Sars, is not 

 improbably, the young of his Mnemia Norvegica, and is charac- 



