10 On the Anatomy of Stephanoceros Eichhornii. 



the Rotatoria, I see a structure, marked with the letter h (on 

 the right at the fore part of the animal), of which the distin- 

 guished histologist confesses that its signiticance was unknown 

 to him. He describes it as ' a group of limpid vesicles which 

 open on the cuticle by a duct, which, although short, is dis- 

 tinct in a suitable position.' Have we not here a similar 

 observation to that which I have frequently made in RotiferV 



There are two points in which this specimen does not agree 

 with the above description. There is no visible duct to the 

 exterior. It is a single vesicle only. I may also remark 

 that I have cut many serial sections of this Rotifer and have 

 only found the parasite present in one instance. 



1 am now engaged in examining Melicerta ringens by 

 means of serial sections, and I hope before long to offer some 

 remarks on that species. 



Literature referred to. 



(1) Hudson, C. T., and Gosse, P. H. The Rotifera or Wheel- 

 animalcules. 188G. 



(2) Rolleston's Forms of Animal Life. Bv W. H. Jackson. (Roti- 

 fera.) 2nd edition. 1888. 



(3) Zacharias, O. " On the Reproduction and Development of 



Rotifer vulgaris" Ann. & Mag. Nat. Hist. vol. xv. no. 80. 1885. 



(4) Eckstein, K. " Die Rotatorien der Umgegend von Giefsten," 



Zeitschrift f iir wissenschaftliche Zoolugie, vol. xxxix. 1883. 



(5) Williamson, W. C. " On the Anatomy of Melicerta ringens" 

 Quart. Journ. Micr. Sci. vol. i. 1853. 



(6) Cubitt, C. " Observations on some Points in the Economy of 

 Stephanoceros," Monthly Micr. Journ. vol. iii. 1870. 



(7) Huxley, T. H. " Lacinularia socialis : a Contribution to the 

 Anatomy and Physiology of the Rotifera," Trans. Micr. Soc. Lond. 

 vol. i. 1853. 



EXPLANATION OF THE PLATES. 

 Plate I. 



Fig. 1. Section parallel to the long axis of Stephanoceros. a, unipolar 

 ganglion-cell placed at the base of an arm with single nerve- 

 fibre ; B, space in arm (body-cavity) ; c, cuticle ; pe, setae ; m, 

 muscles. Zeiss F, oc. 3. 



Fig. 2. A group of unipolar ganglion-cells, showing each ganglion-cell 

 with its single nerve-fibre. Zeiss F, oc. 3. 



Fig. 3. Transverse section of Rotif eron. m, vestibule ; c, taster or tongue ; 

 b, "brain;" e, embryos in section; D, calcareous granules;/, 

 cuticle. Zeiss C, oc. 3. 



Fig. 4. Transverse section of Rotiferon. a, external eye ; b, the deeper 

 eye ; c, calcareous concretions ; D, commencement of mastax : 

 e, cuticle. Zeiss C, oc. 3. 



