M. E. Claparede on Actinophrys Sol. 285 



Exmouth and its vicinity every brook abounds with these crea- 

 tures, adhering Uke limpets to pebbles, and encrusted with a 

 ferruginous deposit from the waters. It is difficult to conceive 

 how they can with safety come to the surface to breathe pure 

 air, as in winter and spring during the freshes, and even in 

 summer, the gentlest current would probably drive such light 

 and delicate animals down the stream, and cause them to perish 

 if they, ventured to quit their moorings ; they must therefore of 

 necessity remain at anchor under the influence of a P«^e//fl-like 

 adhesion, unless they have the power, when they wish to breathe 

 pure air, of veering out a filamentary cable, by which they can 

 withdraw again after respiration to their original site ; or, that 

 they, and all the Limnei, though pulmoniferous, can, from some 

 peculiarity of the respiratory organs, extract, for an almost in- 

 definite time, sufficient vital fluid for aeration. These alterna- 

 tives are not, perhaps, very improbable hypotheses, but at 

 present we cannot determine which of them may solve the diffi- 

 culty. 



The animal, though its habitat is so difi^erent, is infested by 

 the same parasites as the A. ohlongus. We sum up and conclude 

 with the single remark, that both our British Ancyli are con- 

 generic, and have essentially similar organs as all the Lim- 

 neadce, 



I am. Gentlemen, 



Your most obedient servant, 



WiLLTAM Clark. 



XXVII. — On Actinophrys Sol. By E. Clapartjde. 



[Concluded from p. 217.] 



I ASCERTAINED nothing new with regard to the mode of propa- 

 gation of Actinophrys. I have never witnessed decided instances 

 of conjugation, but have often observed circumstances which 

 indicated either a division or a conjugation. One instance of 

 actual division has however occurred to me. KoUiker, Cohn, 

 and Stein have mentioned perfect conjugations. Perty also 

 refers to a similar phsenomenon in his Actinophrys brevipilis 

 {brevicirrhist), and even mentions a mutual conjugation of seven 

 individuals of A, Eichhornii. Stein also speaks of the conjuga- 

 tion of several individuals of his A. oculata, and states that he 

 has found seven individuals in conjugation. It does not how- 

 ever appear probable, from the words he employs, that he saw 

 these seven individuals separate, and it appears to me that we 



