The Genus Synchoeta. By C. F. Eousselet. 281 



ds usually that of cork-screw curves, revolving at the same time on 

 its longer axis, but occasionally turning somersaults in rapid suc- 

 cession for a change. More rarely it is seen to hover over one 

 spot with all its cilia in rapid motion, producing a strong current 

 in the water. It does not, however, anchor itself to a thread 

 secreted from the toes as S. tremula does habitually. Small as is 

 the body-cavity of this rotifer it is not free from internal parasites 

 of considerable size. I have often observed numerous elongated 

 sausage-shaped bodies, 95 fi (^Ij in.) in length by 14 fi (i£ q in.) 

 thick, and also spherical bodies, apparently living on the nutritive 

 fluid it contains, pi. VI. fig. 13. These bodies are not ciliated, have 

 no motion of their own, and consist of a transparent membrane 

 thickly filled with spherical smaller vesicles ; they appear to do 

 little harm to the organs of Synchseta, and the individuals con- 

 taining them seem as vigorous as the others. 



I am greatly indebted to my friend Mr. F. E. Dixon-Nuttall 

 for the very fine figure of this species, pi. III. fig. 1, which he has 

 drawn for me from life. 



The male I have not yet seen, nor have I ever seen any in- 

 dication of fertilised resting eggs which would indicate the presence 

 of the male; but I should mention that Mr. John Hood has 

 doubtfully reported it to me. 



The size of S. pectinata varies between 340 /x (^ in.) and 408 /x 

 •(g 1 ^ in.), but very young animals may be smaller. 



Synchseta tremula Ehrenberg. 

 PI. III. fig. 3. 



BIBLIOGRAPHY. 



Ehbenberg, G. F. — Abhandl. der Akad. d. Wissensch. zu Berlin, 1831, 



pp. 135, 138; 1833, p. 221. 



Die Infusionsthierchen. Leipzig, 1838, p. 438, pi. 54, fig. 5. 



Gosse, P. H. — On the Structure, &c, of the Manducatory Organs in the 



Eotifera. Phil. Trans, of the Eoyal Soc. of London, 1856, p. 434, 



figs. 41, 42. 

 On the Dicecions Character of the Eotifera. Phil. Trans, of the Eoyal 



Soc. of London, 1858, p. 321, figs. 30, 31. 

 Hudson & Gosse.— The Eotifera. London, 1886, vol. i. p. 128, pi. 13, fig. 2. 

 Webeb, E. F. — Faune Eotatorienne du bassin du Leman. Eevue Suisse de 



Zool., Geneve, 1898, p. 394, pi. 16, fig. 17. 



Spec. CJiar. — Body top-shaped, truncate and straight in front ; 

 often yellowish in colour ; auricles small, in line with front of the 

 head ; four frontal styles ; lateral antennae situated at extreme 

 base of body ; eye red, cervical ; foot short, narrow ; toes two, 

 small, acute. Size from 212 fj, (y| - in.) to 292 p (^ 7 in.) in 

 length by 115 fi (^ m -) to 149 fi (p} in.) wide at the auricles. 

 Male conical, 110 /x (■$£* in.) in length ; lacustrine. 



