No. 378.] CLASSIFICATION OF CILIATE INFUSORIA. 427 
In the great diversity of the formation of the body among the 
Gymnostomata we have an interesting analogue with an equally 
wide range among the Zonotricha. 
The highest position must be assigned the Oxytrichidz and 
Euplotide. Here the differentiation of the main feature of 
the ciliates, the cilia, reaches its maximum, not only morpho- 
logically, but also physiologically, combined with the highest 
development of intellectual faculties, as far as we dare speak 
of such. In all these points the Peritricha, which have often 
been placed at the head of the class, are inferior. And their 
inferiority is demonstrated also by the fact that at least half of 
them are epizoa, or commensals ; a large number of animals 
of both categories live in colonies, either actually coherent or 
close together, modes of life which are not so much different 
as is commonly supposed. 
The groups Peritricha,! Gymnostomata, Aspirotricha, Oligo- 
tricha, and Zonotricha seem to have the significance of orders 
of about equal standing with “orders” throughout the animal 
kingdom. Thus we would have the following table : 
SUBCLASSES SUPERORDERS 
Peritricha Peritricha 
f ( Gymnostomata Gymnostomata 
Pantotricha < Aspirotricha 
| Trichostomata (em.) f Oligotricha (em.) 
Zonotricha 
The Ciliata here are regarded as a class. To this point, a 
little digression may be excused. Why should not both Ciliata 
and Suctoria be treated as classes? Conceded that Bütschli is 
right in regarding the tentacles as mouths, and I believe so, 
that would not necessitate ranging them together. The pos- 
session of cilia by the Acinetina, in the early stages of devel- 
opment, has possibly been overestimated. How many features 
are shown, in the earlier or larval stages of other and higher 
animals, to disappear at a later period, e.g., cilia in Mollusca 
(velum) and Echinodermata? If an amceboid stage, or the 
development and disappearance of flagella, were accorded so 
1 The Peritricha might probably be divided into two orders; but, since I have 
not seen Licnophora and Kentrochona, the question is left open here. 
