THE STOMACH AND ITS THREADS. 79 



The pinnee are capable of independent motion ; 

 one being frequently jerked inwards towards the cen- 

 tre of the disk, while its fellows on each side remain 

 motionless. I cannot detect any appearance of cilia 

 on them, nor do I think there are any, for I have seen 

 minute suspended particles slowly sink, till they 

 rested on the pinnae, without the least indication of a 

 vortex or current in the water. 



The beautiful form of the petals above described is 

 quite lost after the animal has been about a day in 

 captivity. In both of my specimens, though the 

 water has been several times renewed, the petals after 

 the first day shrank up into short, thick, unshapely 

 masses, rudely notched at their edges, and never after- 

 wards expanded more than this, though apparently 

 healthy in other respects, and sufficiently sensitive to 

 handling. Probably the defect in extant representa- 

 tions arises from the figures having been copied from 

 specimens in this condition. 



In the centre of the floral expansion a naiTow slit 

 opens into the stomach, a cul-de-sac of the same 

 narrow form, viz. that of a sack when empty, or of a 

 pillow-case as it comes from the laundress, flat, thin 

 as viewed in one aspect, and wide in another at right 

 angles to it. At the bottom it is truncate ; and from 

 hence spring ofi", arching downwards, three threads on 

 each side, which are thickened and much contorted in 

 their course. These threads appear to form the edges 

 of so many delicate membranes, which run up as septa 

 connecting the stomach wdth the exterior parietes of 

 the body, and dividing the whole of the space sur- 

 rounding this viscus into chambers, perfectly isolated. 



