128 THE ROTIFEEA. 



S. TKEMULA. 



(PI. XIII. fig. 2.) 



v hceta tremula . . . Ehrenberg, Die Infus. 1838, p. 438, Taf. liii. fig. 7. 



„ Leydig, Vcb. d. Bau d. Rtiderth. 1854, p. 41. 



„ „ . . . Pritchard, Infusoria, 1861, p. 686. 



SP. CII. Body a slender cone ; coronal head nearly truncate ; auricles scarcely pro- 

 tuberant ; setae four ; no club-shaped prominences; a sudden diminution in girth below 

 I In' i loaca. 



S. tremula is rather smaller than S. pectinata, and its habits are different. It loves to 

 twirl round its own longer axis at the end of a thread stretching from its toes ; and, so 

 twisting, to drift lazily along with the current which bears the object to which it is 

 attached. Its coronal head is almost flat, and the side auricles are nearly in the same 

 plane with it. This makes the animal strikingly unlike S. pectinata in outline. It has 

 no crests on its corona ; only four long curved styles, similar to those of S. pectinata. Its 

 stomach is generally full of a rich brown food, and I have sometimes captured specimens 

 with the oesophagus at the same time stuffed with some pinkish substance. Its eye is an 

 intensely dark-red, and Mr. Gosse has detected a refractive body imbedded in the pig- 

 ment. 1 There is a rocket-shaped antenna (fig. 26) on each side of the trunk just above 

 the foot : organs that 1 have failed to detect in S. pectinata. In all other respects the 

 structure of the two species is almost identical. 



[In one of the shallow evaporating tanks in my orchid house, I found (at the end of 

 May) this pretty species swarming. It plays, by myriads, just above the dull-green 

 floccose sediment that settles on the bottom. 1 learn, from this colony, a habit which I 

 think has not been recognised as proper to this genus — viz. that, like the Brachioni and 

 Anurccc, and one or two other genera, Syncliceta retains its egg after discharge, attached 

 to its own body, just behind the foot. The egg, which I saw, was nearly globular, of a 

 pale yellow hue, granular by the process of segmentation. — P.H.G.] 



I found the male (fig. 2c) in the winter of 1870. It is much smaller than the female, 

 narrower for its length, but otherwise much like her in shape, and with the same four 

 styles on the coronal head. I distinctly noticed in it the entire absence of the nutritive 

 system ; but its irrepressible energy prevented me from obtaining more than a fleeting 

 view of the sperm-sac and penis. 



Length, , J „ inch. Habitat. Clear ponds : common. 



' [On the occipital aspect of the brain-mass is seated an eye-spot, always conspicuous both from its 

 great size and from its intense colour, a red so deep as to be practically black. Its outline varies 

 much ; but normally it is a hemisphere, or rounded cone : often it seems homogeneous, but occasionally 

 we see that it is composed of a multitude of pigment cells agglomerated together and inclosed within 

 a transparent capsule, whose walls I have frequently detected of a thickness greater than that of one 

 of tlie pigment cells. But more than this : I have seen, so often as to have no doubt of its presence, 

 an ovate transparent cell, let-in, as it were, into the coloured body of the eye, the dark pigment rising 

 on each side so as to embrace the base of it. I venture to think this a crystalline lens. — P.H.G.] 



