58 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
the other would amount to nothing less than a metamorphosis, none 
of the steps in which have been observed. 
Another point of difficulty is the entire- absence in the supposed 
young of any partition separating the nucleus-bearing anterior portion 
of the organism from the posterior portion. 
The other forms, resembling those which Leidy thinks may also be 
young of Triconymphi, I have represented in Figures 30-32, 35-39, and 
42-44, I can see no sufficient reason, however, for supposing them to 
be young Trichonymphe. The nucleus of these forms is situated at the 
extreme anterior end of the body. The anterior tip terminates in a 
rounded projection, but it has not the form of the knob seen in Figures 
27 and 29, and a comparison with the cap seen in adult Trichonymphe 
is more difficult in this case than in that of the forms last described. 
The cilia are of very nearly equal length over the entire body. They 
are arranged in bands running spirally around the animal, and the 
spirals run in the same direction (dexiotropic) as in the forms we have 
just been discussing. 
There are, however, so many points of difference between these two 
kinds of supposed young parasites as to render it probable that they 
are not connected with each other genetically any more than they are 
with Trichonympha. It will be observed not only that the nuclei are 
differently situated in the two forms, but also that in those shown in 
Figures 30-32 and 35-38 the interval between successive bands of cilia 
remains nearly constant throughout the entire length of the animal, quite 
unlike the condition obtaining in the other forms. 
This form is also found in a great variety of sizes (Figs. 30, 31, 35), 
the largest being considerably larger than the individuals of the other 
form represented in Figures 27 and 28. The shape of the animal is char- 
acteristic, being in the living condition long and slim. Figures 37, 39, 
and 42-44 represent living specimens. Figure 38 shows one that died in 
normal salt solution. Figures 30-32, 35, and 36 represent the shapes 
they assume when killed with corrosive sublimate. Their method of 
locomotion also serves to distinguish them from the forms which I have 
last described, for they often move, independently of ciliary activity, 
by changes in the form of the whole body (Figs. 39, 42, 44), — some- 
times with the wriggling, squirming motion of a worm, at others, swell- 
ing out in places to almost double their average diameter, and then 
slowly contracting their body-wall (Fig. 44), they produce a kind of 
peristaltic motion, which may aid in locomotion. The smaller ones 
(Fig. 43), when travelling very rapidly in a straight line, revolve around 
