BIOLOGICAL STUDY OF TAP WATER. 421 
PROTOZOA. 
The animal forms belong mostly to the Protozoa, being nearly all 
included in the grcups Rhizopoda and Flagellate Infusoria. 
Rhizopoda.—Among the Rhizopods were noticed at least two 
species of Amoeba 
A. proteus and A. radiosa, but not very fre- 
quently ; on several occasions also Lifflugia globulosa, Actinophrys 
sol, and Acanthocystis turfacea (sp ?). 
Flagellata—Belonging to the Flagellata Infusoria there are a few 
interesting forms, some of which I shall notice in detail. 
Monas lens is occasionally seen, but by far the commonest species 
is Dinobryon sertularia, and a brief description of this beautiful 
animalcule will not be out of place. In the spring and early summer 
they are to be found in large numbers in every filtering, but in 
autumn and through the winter they are rarely met with. 
In the classification adopted by W. Saville Kent, in his ‘“ Manual 
of the Infusoria,” they are placed in the Order Flayellata Eustomata, 
and Family Chrysomonadidae. The characters of the order are as 
follows + “* Animalcules possessing one or more flagelliform append- 
ages, but no locomotive organs in the form of cilia; a distinct oral 
aperture or cytostome invariably developed; multiplying by longi- 
tudinal or transverse fission, or by subdivision of the whole or part 
of the body-substance into sporular elements ;’ and of the family : 
“ Animalcules bi-flagellate, rarely mono-flagellate, social or solitary, 
free-swimming or adherent, naked, loricate, or immersed within a 
common mucilaginous matrix or zoocytium ; endoplasm always con- 
taining two lateral, occasionally green, but more usually olive-brown 
or yellow differentiated pigment bands ; one or more supplementary 
eye-like pigment spots frequently present,” and, as far as at present 
known, they all inhabit fresh water. 
The genus Dinobryon consists of animalcules with two flagella, 
one considerably longer than the other ; attached by a contractile 
ligament to the bottom of a colorless horny lorica, the individual 
loricae being connected together so as to form a colony or compound 
branching polythecium ; endoplasm containing two lateral green 
bands, and a conspicuous eye-like pigment spot situated anteriorly. 
In the species D. sertularia Ehr. the individual loricae are per- 
fectly hygaline and transparent, and are shaped in general like an 
