134 LACINULARIA SOCIALIS 



inch in diameter), which seems to have a thickened wall, and is richly 

 ciliated within. Below this sac, but in contact with it by its upper 

 edge, is a bilobed homogeneous mass (figs. 2 and 4 «) (about i -Sooth 

 of an inch in diameter), resembling in appearance the ganglion of 

 Brachionus, and running into two prolongations below, but whether 

 these were continued into cords or not I could not make out. 



I believe that this is, in fact, the true nervous centre, and that the 

 sac in connection with it is analogous to the ciliated pits on the sides 

 of the head of the Nemertidae, to the " ciliated sac " of the Ascidians, 

 which is similarly connected with their nervous centre, and to the 

 ciliated sac which forms the olfactory organ oi Aniphioxus. 



Mr. Gosse has described a similar organ in Meliceria ringens, and I 

 have had an opportunity of verifying his observations, with the excep- 

 tion of one point. According to this observer, the cilia are continuous 

 from the trochal disc into the cup ; so far as I have obser\'ed, however 

 — and I paid particular attention to the point — the cilia of the cup are 

 wholly distinct from those of the disc. 



The interesting observations of the same careful observer upon the 

 architectural habits of Meliceria would seem to throw a doubt upon the 

 propriety of ascribing to the organ in question any sensorial function. 



But however remarkable it may seem that an animal should build 

 its house with its nose, we must remember that a similar combination 

 of functions is obvious enough in the elephant. 



No eye-spots exist in the adult Lacinularia. In the young there 

 are two red spots on the upper surface of the trochal disc, which are 

 stated by Professor Ehrenberg to be seated upon " medullary masses " 

 (Mark-Knotchen). I could not satisfy myself either of the truth of 

 this statement or the contrary, in consequence of the difficulty of 

 distinguishing the separate tissues in the young animal. 



I may be permitted here to say a word upon the nature of the 

 " calcar," or " respiratory tube," of Ehrenberg, which exists in so many 

 Rotifera. For his first notion, that it is connected with the repro- 

 ductive system. Professor Ehrenberg has substituted the idea that it is 

 a respiratory tube, through which currents of water are conducted into 

 the cavity of the body, and bathe the " trembling organs " which he 

 calls "gills." Professor Ehrenberg, however, has not produced any 

 evidence of such in-going currents, and Dujardin has denied their 

 existence. So far as has yet been observed, the calcar is in immediate 

 connection with the nervous ganglion. Meliceria affords a very good 

 opportunity for examining the structure of the organs, of which in 

 this genus there are two. It is a somewhat conical process of the 

 integument, containing a similar process of the internal membrane. 



