i66 
F. Cavers. 
If stress is laid upon the dual character’of the nuclear apparatus 
—as is done, for instance, by Hickson (1903) who sharply separates 
the Infusoria from the remaining Protozoa under the name Hetero- 
karyota—then two groups of mouthless parasitic forms must be 
excluded. These groups are the Trichonymphidae and the Opalinidae; 
the former are uninucleate, while the latter have numerous small 
uniform nuclei and produce uninucleate gametes. These two families 
are united by Hartog into the group “ Pseudociliata ” and placed in 
the Flagellata; Delage and Herouard place Trichonymphidae in the 
Plagellata, but the Opalinidae are usually retained in the Infusoria. 
Butschli (1887-9) regarded the Trichonymphidae as an isolated and 
independent group derived from Flagellata. Senn (1900) calls 
attention to a number of organisms which in addition to typical 
flagella bear short cilium-like appendages, and suggests that these 
may form a transition between Protomastigineae and the Ciliate 
Infusoria. Unfortunately these forms are still very imperfectly 
known, little or nothing being available regarding their life histories. 
Excluding the Opalinidae, which are probably heterokaryote and 
therefore true Infusoria, we may bring together here a number of 
forms which may be regarded as transitional between Flagellata and 
Ciliate Infusoria, and which might be called “ Cilioflagellata.” 
These forms may be placed close to the Pantostomatineae, from 
which they may be suppossed to have arisen, and they may perhaps 
be considered as a group only little less generalised than the Pan¬ 
tostomatineae themselves, and as having given rise to the remaining 
colourless Flagellata (Distomatineae and Protomastigineae) as well 
as to the Infusoria. Some of the types of “ Cilioflagellates ” are 
represented in Fig. 3. In Trichonympha the whole body, which is 
divided by a constriction into a shorter conical anterior region and 
a longer and wider ovoid posterior region, is covered with long 
flagella ; in Leidyonella the flagella are also numerous but restricted 
to an anterior and a posterior tuft; in Lophomonas they are limited to 
the truncate and hoof-shaped anterior end of the body; in Spironema 
they are fewer and arranged in two lateral groups of about six on 
each side of the anterior pole; in Trichonema there is a single long 
anterior flagellum, with numerous much shorter cilium-like append¬ 
ages either covering the whole of the body (T. gracile) or the 
posterior half (T. hirsutum ); Mitophora is like Trichonema except 
that the “ cilia ” are apparently disposed in a single line running 
nearly the whole length of the body; in Heteromastix there are 
two anterior flagella and a line of “ cilia ” running along about 
half of one side of the body; in Stephanomonas the truncate and 
concave anterior region (mouth-spot ?) bears a long central flagellum 
and a marginal circlet of “ cilia in Pyrsonympha , a parasite, the 
anterior flagellum serve for attachment to the tissue of the host, 
while the “ cilia ” are few and in scattered patches, while in Dinen- 
nympha the whole of the spirally coiled body is clad with “ cilia ” 
and there is no flagellum though the cilia at the anterior end of the 
body are somewhat longer than elsewhere. 
Though practically nothing is known about the genera just 
mentioned excepting their body-form and the general character of 
their appendages, it would seem that we have here forms showing a 
transition from flagella to cilia, or a series of generalised types 
