416 W. E. RITTER AND M. E. JOHNSON 
This, as will be seen by comparing it with our description, is 
the opposite of the condition found in C. affinis, since Brooks places 
the oral ends of the zooids uppermost while we find the aboral 
ends up. This mistake was probably due to lack of sufficient — 
material for the study. He says (p. 87): 
In all my preserved specimens the tip of the stolon had been so much 
flattened by contact with the side of the bottle, in transportation, that 
I have not been able to study in detail the way in which this wheel-like 
arrangement is acquired, and the subject should receive the attention 
of those who are able to study living specimens. 
It is a point upon which one could easily go astray if hampered 
by a lack of material. 
As the changes in internal organization seem to correspond with 
those of C. pinnata, and as Brooks’description is so clear and com- 
plete, we need not go into the subject, but refer to his account 
(Brooks, ’93 pp. 80-106.) 
When the zooid has moved into its secondary position it lies 
upon the stolonic blood vessel rather than to the side or around 
it. With this change, two small vessels develop for each zooid, 
one leading to it from each half of the stolonic vessel (fig. 24, 2bv.). 
The blood flows along one-half of the main vessel (say the upper 
half) out through the upper small vessels to each zooid and returns 
by the way of the lower set of small vessels to the lower half of 
the main vessel where it joins the inflowing current. These cur- 
rents are reversed with the reversal of the blood current in the pa- 
rent. The zooids now increase in size very rapidly, lengthening 
out more above the upper level of the vessel than below it, so that 
at the twist the oral ends extend but a little way below the vessel, 
while the aboral ends extend far above it. Asa result,the aboral 
ends of the zooids of opposite rows come in closer contact than do 
the oral ends. Since the zooids of the two rows are arranged al- 
ternately, each zooid will lie against two of the opposite row. As 
growth continues and the zooids, through their increased size, 
move outward as well as upward, they are forced farther apart, 
but the connection is retained through peduncles which now 
develop. 
