LUCERNARIAD^: : LUCERNARIA. 249 



stricture or short peduncle : the disk even, strengthened by an in- 

 terior cartilaginous lamina, which rises up the short peduncle, and 

 forms a minute hollow firm centre. The margin of the oral ex- 

 pansion is somewhat thickened, and divided into eight equal arms, 

 each furnished with a tuft of numerous short tentacula tipped with 

 a gland, and brighter coloured than the body. The interior is 

 hollowed like the blossom of a flower, the square extensible mouth 

 projecting in the centre; and in the space between the arms there 

 is a complicated structure composed apparently of two series of 

 foliaceous processes arranged on each side of a white line that seems 

 to spring from the sides of the mouth. These processes are formed 

 by the complicated foldings of a thin membrane attached by one 

 side in the manner of a mesentery : there are no vessels in the mem- 

 brane, but some portions of it exhibit, when magnified, a kind of 

 net-work of irregular cells, and the outer and free edge is bounded 

 by a thread-like line. The white central line which divides them 

 is formed of small roundish bodies arranged in two or three close 

 series ; and some of these ova can at times be traced along the 

 margin of the circumference to the tentacula. The latter are cylin- 

 drical and terminated with a globular head, which is seemingly 

 imperforate. The stomach is a loose thin plaited extensible bag, 

 having attached to its inner surface numerous filiform caeca (Fig. 56, 

 c), that, after their removal from the body, retain their irritability 

 for a long time, and writhe themselves like a knot of worms. 



Dr. Coldstream has favoured me with the following observations on 

 the habits of this Lucernaria : " I find the animal very hardy : it is 

 constantly in a state of expansion, and does not contract excepting 

 when very rudely handled. One specimen has lived with me for 

 three weeks, although the water has not been very often changed. 

 When I first procured it, the two rows of spots running from the 

 mouth along each arm were prominent, and of a dark reddish-brown 

 colour. Since that time they have increased in size, and have 

 become studded with numerous white oval bodies which I suppose 

 to be ova. I see some of these have made their way into the web 

 connecting the arms, but I have not observed any expelled from the 

 body." 5th April, 1833. 



OBSERVATIONS. 



The Lucernaria} are of a gelatinous consistence. The skin or 

 corium is smooth and thickish. After covering and giving form to 

 the body it is reflected over the oral disk, and incloses, within the 



