290 Dr. G. C. Wallich on an undescribed Form 0/ Amoeba. 



or destroyed, and both brush-like tuft and pedicle being 

 dragged behind the Amoeba during the entire period. Unfor- 

 tunately the drying-up of the water on the slide put a stop to 

 my observation at this point. 



With regard to the specific value of the characters of this 

 form, I think it unadvisable at present to express a decided 

 opinion. Several circumstances render it probable that it 

 may be a transient phase in the life-history of the common 

 Amoeba. Amongst the principal of these I may mention having 

 detected traces of a like villous structure in specimens obtained 

 from other localities. But, whether the Hampstead form even- 

 tually proves to be a distinct permanent type or otherwise, the 

 characters referred to are of high interest as evincing a nearer 

 approach, than any heretofore noted amongst the Rhizopods, 

 to the structure of the ciliary legs of certain Infusoria, as, for 

 example, of Ploesconia or Kerona*. They also tend to confirm 

 the view put forward by MM. Claparede and Lachmann with 

 reference to the " reptant " nature of the motion of Amoeba, and 

 the consequent suggestion of Dr. Carpenter regarding the pro- 

 bable diflferentiation of the ectosarc into a ventral and dorsal 

 portion. According to present experience, " reptation " takes 

 place in forms endowed with this more highly developed state 

 of a portion of the ectosarc, whilst the motion is of a simple 

 " rolhng " or flowing kind in those forms in which the ectosarc 

 is uniformly developed at all points. 



The Hampstead form corresponds in every important parti- 

 cular with one found by me in Lower Bengal in 1856, in 

 which the villous portion of the ectosarc constitutes a means 

 of permanent attachment to foreign bodies such as Confervse or 

 the like ; and the animal appears to be normally sessile in its 

 habitsf. 



In conclusion, I may mention that a week has passed since 

 the supply of these Amoeba was obtained at Hampstead, and 

 that they retain the characters above described in an unim- 

 paired degree to the hour at which I write. 



EXPLANATION OF PLATE VIIL 

 [Figures 1 to 5 magnified about 400 diameters.] 

 Fig. 1. Amoeba in quiescent or nearly quiescent state: a, villous patch; 

 n, nucleus ; c, contractile vesicle ; v, vacuoles X- 



* See Carter's observations on these forms in the ' Annals and Maga- 

 zine of Natui'al History, 3rd series, vol. iii. p. 241 et seq. 



t This variety is figured in Part I. of my 'North Atlantic Sea-Bed/ 

 pi. 4. figs. 13 & 14. 



X Each letter applies to the same portions of the structure in the several 

 figures. The arrows indicate the direction in which the animal is supposed 

 to be advancing. . 



