FLOSCULAPJAD.E. 45 



rim of the corona. Owing to their great dehcacy, and to their lying in dilferent planes, 

 it is impossible to see nearly all of them at once. They vary greatly in size, position 

 and arrangement ; but their varieties, with those of the forms of the lobes, will be 

 described in the account of each species. 



Volvocina, small Infusoria, and floating particles may constantly be seen to enter the 

 bell-shaped corona, and to pass thence down towards the buccal orifice. The setas take 

 no part in this process, beyond that of preventing the return of the captured prey, by 

 interlacing in a close network over the top of the cup, or by individually lashing at a 

 returning object, so as to throw it back again into the gulf. The interlacing of the setse 

 is accomplished by the heads of the lobes approaching each other, and, should the prey 

 be large and vigorous, the lobes are pressed tightly together, so as to completely bar 

 all chance of escape. In most of the species, the motion of the setfE appears due to the 

 fitful action of the cuticle, on which they are placed ; but in F. trilobata, F. Iloodii, 

 and notably in F. viutabilis, a regular cilia-like motion occurs in the sets ; while in 

 F. mira there is a still wider departure from the ordinary type ; since in this Floscule 

 each seta has a constant, slow, independent, ama>boid motion. 



The Vestibxile.— At the bottom of the corona is a second chamber (the vestibule), 

 bovmded above by a highly contractile collar, below by a diaphragm with a slit in its 

 centre (the buccal orifice), and on the sides by thick walls. On the upper margin of the 

 collar, and running half round it on the ventral side, is a horse-shoe-shaped ciliated rim, 

 ending in two knobs, bearing long, slowly moving cilia ; and this rim is so set, that it 

 slopes downwards from the dorsal side to the ventral. This true rotatory apparatus 

 may be easily seen in the large Floscules F. Hoodii and F. trilobata.^ 



A current, due to the action of these cilia, sets down the coronal cup, in a plane at 

 right angles to its base, and carries the food, past the collar, into the vestibule. When 

 once an organism has reached the vestibule, there is no return for it to the upper world. 

 The Floscule often sufljers two or three small Infusoria &c. to wander about round 

 the walls of the vestibule ; but at any attempt to pass the collar, that at once contracts 

 on itself, and closes the passage. In the diaphragm, which is the base of the vestibule, 

 there is a long slit, the buccal orifice, bounded by two chitinous lips (PI. I. fig. Id, Ip), 

 from which there hangs into the next chamber, called the " crop," an clastic tube (PI. II. 

 fig. 4, ^1, which may be seen always midulating above the uiastas. When there are 

 victims enough collected in the vestibule to make it worth while to swallow them, the 

 collar contracts violently, the lips dart forward with a sort of snap, and the prey is 

 forced down the tube into the crop. It is evident that this hanging tube is an admir- 

 able contrivance for admitting fresh prey into the crop, while at the same time pre- 

 venting the return of that previously captured. Naturalists plagiarise from the Floscules, 

 when they drop their live specimens through a quill stuck into the cork of a bottle ; 

 only the rigid quill is far inferior to the flexible and ever-moving tube. 



The crop (PI. II. fig. 4, c-p) is a rounded chamber just under the diaphragm at 

 the base of the vestibule. It has very thick walls, which are strengthened externally 

 by two granular spots one on either side of the Floscule's shoulders (PI. I. figs. 4, 8a). 

 Viewed as opaque objects they are white, like the similar oval knobs on Mcijalotrocha 

 alhoflavicans. 



Under the action of small muscular fibres, the sides of the crop contract alternately, 

 and throw the contained food from side to side ; by which means every part of it in turn 

 is subjected to the action of the jaws (PI. II. fig. 4, ti). These lie at the bottom of the 



' Dr. Dobic clc^icribod the two ciliatfid knobs in F. canqmnulata., Ann. Nat. Hist. 1810. Mr. Gosse 

 inferred the existence and position of tlie true rotatory organ from the motion of particles in the 

 coronal cup (Tcnbi/, \i. o07). Dr. Moxon says that "the alimentary canal above the gizzard is divided 

 by a highly irritable cilium-clothed spliincter of irregular outline " {Trans. Linn. Soc. vol. xxiv. IHfil, 

 p. 4,57). In 181)7 1 published a full description of the rotatory organ of F. camjxmulala in the Trans. 

 Brhtol Mkr. Soc. In IbOU Mr. Cubitt did the same for btei^hanoccros and F. coronclta (Mon. Micr, 

 J. vol. li. 1860, p. 133). 



