of England and India. 21 
but the Amebe, and the next morning presented absolutely no- 
thing but Coleps.. The “rains” then set in, filled the tank, 
and destroyed all trace of these Amabe, since which period I 
have never met with a similar occurrence. 
Ameba monociliata, n.sp. Pl. II. fig. 19. 
Polymorphic, charged with granules ; possessing a single large 
cilium and villi on the posterior extremity. 
Hab. Fresh water. Locomotion reptant. 
Loc. Bombay. 
Obs.—I remember this specimen well. It stands figured in 
my journal for May 1855 under two forms, as represented in 
the plate, with no mention of the size, or anything more than 
has been above stated. In the presence of the flagelliform organ 
we seem to have perpetuated the one or two cilia with which the 
young or monadine forms of the Rhizopoda, so far as my know- 
ledge extends, are generally provided, but which disappear as 
they grow older, leaving the more developed form inferior in 
point of locomotive organs to the less matured one. Whether 
the cilium of A. monociliata could be retracted or not I am not 
enabled to decide, because I never observed more than one 
specimen. But that we have an instance of this power in the 
Rhizopoda is seen, not only in the young of Acmeta (which, 
on issuing from the parent, commence with cilia which finally 
become retracted and give place to capitate tentacula), but also 
in the division of the free or stemless species, where one half 
only puts forth cilia till its separation is thus completed, and 
then retracts them again, to be followed by tentacula, as in the 
young one—a fact which is well worth remembering, whether it 
bears upon the question of A. monociliata being able to retract 
its cilium or not, since it affords another instance of the extra- 
ordinary extemporizing power of the Rhizopoda, viz. that of 
being able to put forth vibratile cilia and retract them as the 
occasion may require—organs which, in the other Infusoria, 
when once developed, appear to be as unalterable in form as 
their motions seem to depend on fixed muscular machinery. 
It is possible that this so-called species may be but a variety 
of Podostoma filigerum, Clap. et Lachm. (p. 441, pl. 21. figs. 4-6) ; 
but, as above stated, I never saw but one specimen, and this did 
not remain sufficiently long under observation to undergo more 
changes in form than those which I have figured. 
Dirrivera, Ehr. 
Difflugia pyriformis, Perty (mihi). 
A detailed description of this species will be found in the 
‘Annals’ (ser. 3, vol. xii. p. 249), and I have nothing further to 
