41 THE ROTIFERA. 



tubes in juxtaposition, and the whole group can then be well shown under a low power; 

 the animals, in various positions and under different aspects, forming, with their delicate 

 cases and interlacing seta?, a picture that can be hardly rivalled. 



F. campanulata, when fully expanded, has been compared to " a Ions tubular flower 

 with a. five-angled petal, the tube swollen, contracted below the lip, and seated on the 

 end of a long stalk." ' This description applies very well in most respects to the other 

 species, except that the number of petals is not always five ; for, owing to late discoveries, 

 there is now a regular series of Floscules with seven, five, three, and two lobes; and 

 one species in which the corona is not divided into lobes at all. 



The set;e also, which crown the lobes, and are so highly characteristic of the better- 

 known forms, \ary quite as much in the newer species as do the corona. 1 ; in some 

 exceeding the Rotiferon's utmost length, and in others diminishing almost to the size of 

 ordinary cilia. Indeed, if the strange genus Acyclus— which must be very closely allied 

 to the Floscules — be also taken into account, as well as the equally curious genus 

 Apsilus, there is a tolerably complete series of forms showing a gradual change from a 

 Floscule, with seven loins, and long radiating seta?, to a Floscule-like Rotiferon in which 

 the seta) have entirely vanished, the corona has degenerated into a very delicate 

 protrusile cup, and even the foot itself has shrunk into a mere sucking disk. 



The Tube. —The Floscules inhabit a semi-transparent gelatinous tube, into which 

 the animal when alarmed can contract itself with great swiftness. It is secreted by the 

 creature itself, and moulded on its own body by its sudden contractions, and slow 

 expansions. When free from diatoms and extraneous particles (which is seldom the 

 case), it is difficult to be seen, especially by transmitted light : under the dark-field 

 illumination, not only can its outline be seen, but the substance of which it is composed 

 can be traced from the outer surface, far in towards the Rotiferon itself. The tube 

 becomes thinner towards the top, and it is often difficult to trace it there ; but it will 

 generally be found to close in neatly a little under the neck. 2 



A Floscule, emerging from its tube, after one of its contractions, presents the appear- 

 ance of a pear-shaped body on a transversely wrinkled stalk, with a pencil of long 

 parallel hairs rising from the puckered centre of the rounded upper end. It slowly 

 stretches itself till the wrinkles of the foot have nearly disappeared ; and then, after a 

 delay, sometimes provokingly long, the puckers round the seta- relax, and the whole pencil 

 is thrust forward, by the unfolding of the lobes of the corona ; which, as they rise, show 

 that they had been drawn down into the body by inversion, as the tip of the finger of a 

 glove may be drawn into it, by pulling it from within. After a little further hesitation, 

 the lobes unfold, and expand into a wide cup, while " the setse seem to fall round it on all 

 sides in a graceful shower." The now fully expanded Floscule consists of five well- 

 marked portions; the corona, the vestibule, the crop, the trunk (including the viscera), 

 and the foot. 



The corona is a delicate nearly hemispherical cup, whose free edge is cut into 

 lobes varying much in sitae, shape, and number. There are two main varieties of lobe ; 

 in the one they are narrow, pointed, and ending in a spherical knob; in the other they 

 are broad, bounded by low convex curves, and knobless. In almost all, the dorsal lobe 

 is conspicuous by its greater size, or peculiar appendages. The corona is furled by the 

 action of delicate muscular threads imbedded in its surface, and expanded by the upward 

 rush of fluid between its outer and inner integuments, due to the contraction of the 

 transverse muscles of the trunk. 



The setae are set either on the knobs that crown the summits of the lobes, or on a 

 thick rim running round them ; and they sometimes form a continuous fringe on the 



1 Gosse, Popular Si i. Eev. vol. i. 1862, p. 160. 



- Though the tube is of the flimsiest material, and lighter than water, it certainly protects the 

 animal from its enemies. I have watched a sharp-jawed larva trying to bite through a 1'loseule's tube, 

 and it wa ! as completely foiled by its swaying about from side to side at every touch, as a boy at Hallow 

 E'en ib baffled by a floating apple, when trying to seize it with his tei tli. 



