132 Proceedings of the Royal Society of Victoria. 



F r (J 111 these appearances I conclude the t a j^ 

 to consist of a flattened funnel closed at one 

 end by a protoplasmic mass, to which is 

 a 1 1 a c li e d a n "undulating ni e m b r a n e " lying 

 between two thin, delicately striated walls, 

 to which it is joined on each side for its 

 whole length, being free only at the narrow 

 proximal end of the tag, and dividing the 

 interior of the tag into two separate cavities 

 or pockets. 



In the references which I have been able to make to the 

 literature of the subject, I find considerable disagreement as to 

 the nature of the internal structure Dr. Hartog^ states, that : 

 " The probable explanation of the two distinct wave appearances 

 within the tag is that the protoplasmic plug bears on its inner 

 face a row or tuft of long cilia hanging down into the cavity of 

 the tag." Dr. Zelinka figures and describes- the vibratile tag of 

 Callidiua russeola as containing a cylindrical mass of closely 

 agglutinated cilia, and estimates the number of such vibratory 

 hairs. He also quotes Moebius as having recognised the compo- 

 sition of the flagellum from numerous cilia. He further gives 

 an abstract of a description of the vibratile tags in Asplaiichna 

 amphora by Mr. C. Rousselet, who definitely regards the 

 vibrating structure as an " undulating membrane," and suggests 

 that the spongy protoplasmic cap is " probably quite open enough 

 to allow some part of the fluid of the body cavity to pass through 

 into the tags." Dr. Hudson^ asks " Are the vibratile tags open 

 at their free ends or are they closed. Do they contain an 

 undulating membrane, or are their inner surfaces furred with 

 minute cilia 1 " Dr. Weber^ describes the tags of Hydatina senta 

 as a flattened l)ell, with a cleft at the upper part surrounded by 

 a pad armed with short cilia, while below are two thickenings 

 each furnished with a long cilium. He figures these cilia with 

 undulations crossing each other. He also states that all tl\e 



1 Cambridge Nat. Hist., vol. ii., p. 213. 



2 Zeit. fur VViss. Zool., vol. liii., p. 22. 



3 The Uotifera, vol. ii. Appendix, p. 1.37. 



4 Notes sur (iuel<iues Rotateurs des Environs de GenOve, p. 



